Cell Synchronization - (Nov/13/2009 )

Hi,
This is for all of you who do hormone treatments for mammalian cells. I know some people (seems like it is the majority) synchronize their cells before treatment, but I, personally, don't and I do not think this is a crucial point unless you are particularly interested in cell-cycle regulation or cell-cycle-related aspects of the hormone under study. I would appreciate if you guys write some comments if synchronization is otherwhise important.

What about periodic hormone production such as estrogen?