ESR1 and breast carcinoma: Interestingly, 24,25 (OH)2D3, which is often considered as a functionally inactivated vitamin D metabolite, could also exhibits anti-cancer properties in ER+ breast cancer cells, but not in ER− breast cancer cells, suggesting that the anti-cancer effect of 24,25 (OH)2D3 may be ER-dependent (Verma et al., 2021).