Human glutathione S-transferase P1-1 functions as an estrogen receptor α signaling modulator.

•GSTP induces the classical ERα signaling event.•The functional GSTP is a prerequisite for GSTP-induced ERα transcription activity.•The expression of RIP140, a transcription cofactor, was inhibited by GSTP protein.•We propose the novel non-enzymatic role of GSTP.