GPER1 and neoplasm: With regard to studies suggesting a tumor-suppressive role of GPER-1 in TNBC, one report claimed GPER-1 agonist G-1 to inhibit TNBC cell growth via induction of cell cycle arrest in the G2/M phase, enhanced phosphorylation of histone H3, and caspase-3-mediated apoptosis [69].