Hi May, you will need to normalize for viable cells in each well. I would recommend that you use a colorimetric reagent such as CellTitreBlue (Promega) or other which do not interfere with Oil Red O (you'll have to do your own research on this). Then you can plot % of LIVE positive cells vs treatment. Otherwise, you could try double staining and FACS analysis but this is a bit more complex. Potentially, you could differentiate between live and dead positive cells.

Sorry I misspelled your name Mai. It'd be good to be able to edit these posts.

Thank you for your suggest. But I still consider that, after I stained cells with Oil Red O solution, cell already died. At that time, should i use a colorimetric reagent such as CellTitreBlue (Promega) to get the signal?

If I understand your experiment correctly, I would do it after drug treatment and just prior to Oil Red O staining. CTB will give an approximate number of life cells in the well and Oil Red O the number of adipocytes. Its not perfect, as you won't be discriminating live vs dead Oil Red O positive cells but it will help you normalise the signal. Otherwise a variation in the number of Oil Red O positive cells could actually be masking a difference in cell viability.

*live cells

Oh, now i see what you mean. It means that:

After i treat Docetaxel and Doxorubicin for enough time, i should treat CellTitreBlue to check cell viability first. And then, i can stain with Oil Red O for adipocyte differentiated-cells, right? I will try as you suggest. Thank you for your help Fernando.

No worries.

Could you not just quantify the protein? (unless you are trying to keep the stained cells)

I do: differentiate cells, stain cells, take pictures, quantify stain with absorbance, then quantify total protein to normalize ORO absorbance.