ESR1 and breast cancer: PGZ-activated PPARγ targets estrogen receptors (ER) and aromatase, activates the tumor suppressor gene PTEN to inhibit ER expression or induce proteasome-dependent ER degradation, and inhibits aromatase through PGE2 and BRCA1 signaling pathways to prevent breast cancer progression (Margalit et al., 2012).