ABCB1 and neoplasm: CD44 interacts directly with the cytoskeleton via ERM proteins (ezrin, radixin, and moesin) and supports the survival and maintenance of CSCs by engaging tyrosine kinase receptors such as ERBB2 and MET.14 Additionally, proteolytic cleavage generates the CD44 intracellular domain (CD44ICD), which participates in intracellular signaling pathways.15 CD44-positive CSCs promote tumor growth through pathways such as Wnt/β-catenin and MAPK, while also acquiring therapeutic resistance by upregulating drug efflux pumps such as MDR1 and P-glycoprotein.