DNMT1 and breast carcinoma: To test this hypothesis, we evaluated breast cancer cell lines representing ER+ (MCF7), HER2+ (BT474), triple-negative (HCC1395), and claudin-low (BT549) subtypes of breast cancer for their response to a next-generation DMTi (guadecitabine; 7 day treatment) which targets DNMT1. In all cases, MHC-I expression at the cell surface was enhanced in a dose-dependent manner after subsequent stimulation with IFNγ (Fig. 1b).