Although ruxolitinib and calcitriol as single agents consistently exhibited significant anticancer effects in breast cancer cells with different molecular subtypes in our study, the combination of ruxolitinib and calcitriol showed a synergistic effect in HER2-enriched subtype SKBR3 and TN subtype MDA-MB-468 cells but did not show any synergistic treatment effect in luminal A subtype MCF-7 cells on cell proliferation and apoptosis analyses. The gene discussed is ERBB2; the disease is breast cancer.