Fig. 5.

Dynamics of expression of selected groups of primary target ERE(+) proteins and secondary response ERE(-) proteins in the presence of increasing concentrations of 4-hydroxytamoxifen. Four biological replicates of MCF-7 cells were stimulated with 10 nm 17β-estradiol in the presence of increasing concentrations of 4-hydroxytamoxifen, grown for 36 h and analyzed by SRM. Expression of true primary targets and secondary response proteins was inhibited at 100 nm concentration of 4-hydroxytamoxifen. IC50 of 4-hydroxytamoxifen was estimated at 15 nm. Levels of two house-keeping proteins ACTB and GAPDH are presented for comparison. *Cells treated with vehicle control (0.1% ethanol) and 10⁻⁶ m 4-hydroxytamoxifen. a.u., arbitrary units.