In MCF-7, HER2-overexpressing, p53 wild-type ER-positive ZR-75-1 and p53 mutant Hs578t cells (a breast tumor cell line intrinsically radioresistant), calcitriol and its analog EB1089 have been shown to sensitize cells to radiation by promoting cytotoxic autophagy. This evidence concerns the gene TP53 and breast neoplasm.