I think the answer to your question will depend on what exactly question tyou are trying to answer in your experiment and the drugs you are using.

   If you serum starve to synchronize the cells and introduce your drug during serum starvation, your drug will have a chance to act in the absence of a proliferative signal. If you are looking to prevent G0 exit and entry in G1, when you reintroduce serum or some other proliferative signal, this may be the way to go. Depending on the drug and the target you are interested in, you also might need to supplement the serum containing medium with the drug as well to maintain the drug action.

   If you add your drug to the cells via the medium when you stimulate re-entry into the cell cycle, you will then see the action of the drug only in the presence of a proliferative signal.

    In practice for many experiments, this may not be a critical difference.

    I think the answer to your question will depend on what exactly question tyou are trying to answer in your experiment and the drugs you are using.

   If you serum starve to synchronize the cells and introduce your drug during serum starvation, your drug will have a chance to act in the absence of a proliferative signal. If you are looking to prevent G0 exit and entry in G1, when you reintroduce serum or some other proliferative signal, this may be the way to go. Depending on the drug and the target you are interested in, you also might need to supplement the serum containing medium with the drug as well to maintain the drug action.

   If you add your drug to the cells via the medium when you stimulate re-entry into the cell cycle, you will then see the action of the drug only in the presence of a proliferative signal.

    In practice for many experiments, this may not be a critical difference.

Hello

I agree with David M Sherry , and kindly look at links here may help you

Good Luck

https://www.researchgate.net/post/Is_it_necessary_to_starve_the_cells_prior_to_any_drug_treatment2

https://www.researchgate.net/post/What_is_the_time_frame_for_serum_starvation_followed_by_cell_signaling_detection

I write to point out that it is impossible, as in not possible at all, to synchronize cells by whole-culture methods where you starve, inhibit, arrest or do everything to all cells and then release them.  These cells are not synchronized at all.  Here are some papers you should read and if you cannot get these papers write to me at

[email protected]

and I will send you all the papers in pdf format.  Also look at criteria below, particularly number 8 which is never fullfilled in whole-culture methods.  I know the field believes otherwise, but the field is wrong.  In parituclasr look at the Rethinking Synchronization paper and the perpetual motion paper.

Stephen Cooper

[email protected]

11.       Cooper, S. (2003). Rethinking synchronization of mammalian cells for cell-cycle analysis. Cell Mol Life Sci 6, 1099-1106.

12.       Cooper, S. (2003). Reappraisal of serum starvation, the restriction point, G0, and G1-phase arrest points. FASEB J 17, 333-340.

13.       Cooper, S. (2004). Rejoinder: whole-culture synchronization cannot, and does not, synchronize cells. Trends Biotechnol 22, 274-276.

14.       Cooper, S. (2004). Is Whole-culture synchronization Biology's "Perpetual Motion Machine"? Trends in Biotechnology 26, 266-269.

15.       Cooper, S. (2005). Reanalysis of the protocol for in vitro synchronization of mammalian astrocytic cultures by serum deprivation. Brain Res Brain Res Protoc 15, 115-118.

16.       Shedden, K., and Cooper, S. (2002). Analysis of cell-cycle-specific gene expression in Saccharomyces cerevisiae as determined by Microarrays and Multiple synchronization methods. Nuc Acids Res 30, 2920-2929.

17.       Shedden, K., and Cooper, S. (2002). Analysis of cell-cycle-specific gene expression in human cells as determined by microarrays and double-thymidine block synchronization. Proc Natl Acad Sci USA 99, 4379-4384.

18.       Cooper, S. (2000). The continuum model and G1-control of the mammalian cell cycle. Prog Cell Cycle Res 4, 27-39.

19.       Cooper, S. (2005). The continuum model of the eukaryotic cell cycle:  Application to G1-phase control, Rb phosphorylation, Microarray analysis of gene expression,a and cell synchronization. Clinical Oncology 26, 205-206.

20.       Cooper, S., and Shedden, K. (2007). Microarrays and the relationship of mRNA variation to protein variation during the cell cycle. J Theor Biol 249, 574-581.

22.       Cooper, S. (2017). Rethinking cell-cycle-dependent gene expression in Shizosaccharomyces pombe. Antonie van Leeuwenhoek 00, 000-000.

23.       Cooper, S. (2015). Gene Expression During the Cell Cycle: Obfuscation of Original Cell-Cycle Gene Expression Data by Normalization. Journal of Cells 1, 1-7.

24.       Cooper, S. (2017). The Ideas of Ludwik Fleck and their Application to the Eukaryotic Cell Cycle. Studia Historiae Scientiarum (The Work of the Commission for the History of Science PAU) 16, 000-000.

25.       Cooper, S. (2004). Whole-culture Synchronization Can Not, and Does Not, Synchronize Cells. Trends in Biotechnology 22, 274-276.

26.       Cooper, S., Iyer, G., Tarquini, M., and Bissett, P. (2006). Nocodazole does not synchronize cells: implications for cell-cycle control and whole-culture synchronization. Cell Tissue Res 324, 237-242.

27.       Cooper, S., and Gonzalez-Hernandez, M. (2009). Experimental reconsideration of the utility of serum starvation as a method for synchronizing mammalian cells. Cell Biol Int 33, 71-77.

28.       Cooper, S. (2002). Reappraisal of G1-phase arrest and synchronization by lovastatin. Cell Biol Int 26, 715-727.

29.       Cooper, S. (1998). Mammalian cells are not synchronized in G1-phase by starvation or inhibition: considerations of the fundamental concept of G1-phase synchronization. Cell Prolif 31, 9-16.

30.       Cooper, S., Chen, K.Z., and Ravi, S. (2008). Thymidine block does not synchronize L1210 mouse leukaemic cells: implications for cell cycle control, cell cycle analysis and whole-culture synchronization. Cell Prolif 41, 156-167.

31.       Cooper, S. (1979). A unifying model for the G1 period in prokaryotes and eukaryotes. Nature 280, 17-19.

32.       Cooper, S. (1982). The continuum model: statistical implications. J Theor Biol 94, 783-800.

33.       Cooper, S. (1987). On G0 and cell cycle controls. Bioessays 7, 220-223.

40.       Cooper, S., and Shedden, K. (2003). Microarray analysis of gene expression during the cell cycle. Cell & Chromosome 2, 1-12.

Criteria for successful synchronization of cells

1) If newborn cells are produced by the synchronization method, there should be a

minimal increase in cell number for a period of time covering a significant fraction

of the interdivision time.

2) The rise in cell numbers during division should occur over a relatively small

fraction of the total interdivision time. It may be as small as 10% for 90% of the

final rise in cell number, or it may be as large as 20-25%. Knowing this value is

important in judging a synchronization procedure.

3) At the time of synchronous division, the cell number should double. If cell number

does not double, that means some cells are dead or altered; this minority of cells

could be giving results that obfuscate the results emanating from the majority of

dividing cells.

4) There should be at least two successive cycles available for analysis. If only one

cycle is analyzed, the results may merely reflect artifacts or perturbations

resulting from synchronization. Presumably, but not necessarily, these artifacts

would be eliminated in the second cycle.

5) Successive generations (i.e., the time between rises in cell number) should be of

equal length and equal to the doubling time of cells in exponential growth.

6) Data points should show synchrony without any need to connect points or draw

a suggestive line indicating synchrony. The data should speak for itself.

7) The DNA distribution of cells should be narrow in the synchronized cells and

these distributions should then reflect the movement of cells through the division

cycle. Thus, newborn cells should be essentially pure cells with a G1-phase

amount of DNA, the DNA content should then move through S-phase contents,

there should be a period of time when cells have only G2-phase DNA contents,

and then there should be a return to essentially pure G1-phase DNA contents.

8) The size distribution of newly synchronized cells should be narrower than the size

distribution of the original population, cell size should increase as the cells move

through the cell cycle, and during the period of cell division there should be a

bi-modal distribution of cell sizes.

9) Cell numbers should be determined by a method that eliminates investigator bias.

For example, electronic cell counting is to be preferred to microscope counting

chambers.

10) Only selection methods can give synchrony. Whole-culture methods, using

inhibition or starvation, cannot synchronize cells. This is not so much a criterion,

as a theoretical rule regarding synchronization in general.

11) Alignment of cells so that cells all have a particular property in common (e.g., all

cells have a G1-phase DNA content) does not mean that the cells are

synchronized. Synchronized divisions are the sine qua non of synchrony.

Criteria for successful analysis of gene expression during the division

cycle

12) Gene expression results should be replicated (with allowance for normal

synchrony decay) in successive cycles. If data does not repeat over two or more

cycles, the cells are very likely perturbed by the synchronization method.

Thank you all for the valuable suggestions. 

Dr. Cooper! I will go through the papers and will definitely let you know if I required any PDF copy.

Just a thought. If we are not  synchronizing the cells by serum starvation, are we un-intentionally selecting the side population or inducing resistance in them?