you can choose any of these methods

http://www.genpharmtox.de/downloads/CYPProfAssaySheet.pdf

http://www.jbmb.or.kr/jbmb/jbmb_files/[38-3]0506010949_366.pdf

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1224698/pdf/S1110724305411043.pdf

http://bmbreports.org/jbmb/jbmb_files/[36-3]0305281542_332-335.pdf

http://jbx.sagepub.com/content/13/2/135.full.pdf+html

http://www.currentprotocols.com/protocol/tx0427

save this for ur reference(thesis)

dspace.mit.edu/bitstream/handle/1721.1/38759/34664657.pdf?

http://thesis.library.caltech.edu/2469/2/cirinothesis.pdf

if u hav access to nature magazine via ur institution get this article

http://www.nature.com/nprot/journal/v4/n9/full/nprot.2009.121.html

Thanks a lot Muhammad Yasar...I will try these protocols

you mean to say, enzymatic activity of cyps---- you have different kits available for each enzyme and do RT-PCR for each cyps to determine rna levels

I meant enzyme activity, Aparna.......

For RNA expression levels studies ....could you suggest kits for CYP1A1, CYP1A2, CYP3A1, CYP3A4...which commercially available kits are the best?Have you worked on these enzymes?