CD44 and breast carcinoma: Some studies have shown that the Stat3 signaling pathway is required for growth of CD44+CD24– stem cell–like breast cancer cells21, such as several basal-like breast cancer cells (MDA-MB-231, BT-549, HCC1937, Hs 578T, MDA-MB-468, and SUM159PT ), not expressed in luminal breast cancer cell lines (BT-474, MCF7, MDA-MB-453, SK-BR-3, T-47D, and ZR-75-1)22.