hi

you should use between 1-10nM range, but you should grow the cells in charcoal stripped serum (5%) for 48-7hours previously, to allow responsive genes to be downregulated to baseline.

The concentrations of E2 or DHT ranged 0.1 nM to 10 nM would be ok, since the maximal plasma levels of endogenous E2 and DHT in our human being are between 0.1 M and 10 M. Moreover, to eliminate the effects of the endogenous estrogenic or androgenic components on gene expression in the medium and FBS, the medium should be changed to phenol red-free medium containing 2-10% charcoal/dextran-filtered fetal bovine serum (CD-FBS) for 48 h prior to experimentation. The used concentrations of CD-FBS are depend on the cell types. We often used 2% CD-FBS for HepG2 cell lines,  5% for MCF-7 cell lines, and 10% for SK-BR-3 cell lines.