Cell Proliferation: To adhere or not to adhere (before treatment), that is the q - (May/14/2010 )

I am running a cell proliferation assay as well as trying to determine if my cells release VEGF. Ultimately, I want to know if my drugs can inhibit both of these processes. I have read many papers and some say that they allow the cells to adhere for 24 hours (or 12 hours) before giving them treatment and some say they just add the treatment right after they plate the cells. Is there a difference? Is one way better than another? Why do you have to allow them to adhere first? I am using Lewis Lung Carcinoma cells if this makes a difference. Please help!!

Thanks in advance.

If you don't let them adhere when they are normally adherent, then the drug might stop them from adhering resulting in abnormal expression of genes/cells dying.

Thanks for the advice. I might run it both ways and find out.