DLL1 downregulation promotes apoptosis of MCF-7 cells. (A-C) MCF-7, BT474 and MDA-MB-231 cells were not-transfected (NT) or transfected with DLL1-siRNAs (DLL1-si1/2), or negative control (Ctr) siRNA. At 92 hours (MCF-7) and 120 hours (BT474 and MDA-MB-231) after transfection cells were collected, stained with annexin-V and apoptosis analyzed by flow cytometry. Representative dot plots showing the percentage of apoptosis at each condition are represented. Graph shows percentage of apoptosis (mean + SD) of at least three independent assays, each one performed in triplicate. *, P