ESR1 and cancer: In particular, ERα‐36 initiates rapid, non‐genomic signaling pathways that activate the PI3K/AKT, MAPK, and PKC pathways, which further induce the expression of cell cycle genes, such as cyclin D1 and cyclin‐dependent kinases, thereby promoting cell proliferation and enhancing the metastatic potential of cancer cells (Fig. 4) [12, 30].