CD44 and breast cancer: MUC1 is highly expressed in AML stem cells, pancreatic CSCs, and breast CSCs; MUC1 overexpression increases stem cell properties in cord blood CD34+ cells and breast cancer cells; MUC1 is overexpressed and hypoglycosylated in the side population of MCF7 breast cancer cells; Staurosporine-induced apoptosis activates CD44+/CD24− breast CSCs by upregulating MUC1 and EpCAM.