CD44 and colorectal carcinoma: Colorectal CSCs can be identified by a variety of cell surface markers, including CD133, CD44, and CD24.4,5 Persistent activation of canonical Wnt signaling is crucial for the tumorigenesis of CRC (refs. 6,7) and stemness maintenance of colorectal CSCs.8,9 Wnt signaling is activated when Wnt ligands bind to the membrane receptors Frizzled and LDL receptor-related protein 5 or 6.