Figure 1.

17β-estradiol (E2) induces Heat Shock Factor 1 (HSF1) phosphorylation on S326 in ERs/GPR30-positive MCF7 cells but not in ERα-negative mammary cells. (A) Expression of estrogen receptors, ERα, ERβ, and GPR30, as well as HSF1 in human mammary non-tumorigenic (MCF10a and MCF12a) and tumorigenic (MCF7, SKBR3, MDA-MB-468, and BT549) cells. (B) The above cell lines were treated with 10 nM E2 for one hour or two hours and the whole-cell extracts were analyzed by western blot. The right panel shows the results of densitometric analyses. An asterisk indicates a significant difference (p < 0.05) from the control (Ctr) value. ACTB and HSPA8 were used as controls for protein loading. Numbers below blots represent protein bands’ intensity ratios to adequate controls after normalization against ACTB.