CD44 and breast carcinoma: First, FACS analysis of CD44, a well-recognized marker of breast cancer stem cells, demonstrated that MPA induced a large and highly reproducible CD44+ shift in T47-D cells, suggesting that MPA induces an increase in stem cell- or progenitor-like cells, as previously shown (Horwitz and Sartorius 2008; Al-Hajj et al. 2003; Axlund and Sartorius 2012).