GPER1 and breast cancer: The activation of GPER has been shown to inhibit melanoma cell proliferation, as well as that of prostate and 17β‐estradiol–stimulated breast cancer cells.[32] In melanocytes, GPER‐mediated signaling enhances melanogenesis by elevating intracellular cAMP, which in turn activates protein kinase A (PKA) and leads to CREB phosphorylation and upregulation of the microphthalmia‐associated transcription factor (MITF) (Figure3).