Meso-octamethylcalix-[4]-pyrrole (C4PY), a GPER antagonist, was found to inhibit E2 and G-1 mediated c-fos activation and EGR1 promoter activities in SKBR3 breast cancer cells as well as cancer-associated fibroblasts (CAFs) (34). Here, FOS is linked to breast carcinoma.