MAPK3 and cancer: As the MAPK pathway triggers the transduction responses mediated by both estrogen and insulin signaling in cancer cells,14, 16 we noted that either ICI (Figure 3E,H and S1C) or OSI‐906 (Figures 3F,G and S1BC) prevents the ERK1/2 phosphorylation by both E2 and insulin in BCAHC‐1 cells.