CD44 and neoplasm: Cell-adhesion molecule. Expression in normal tissues is low. In addition, CD44 is expressed on endothelial and mesenchymal cells. CD44+ cells showed increased self-renewal ability and increased ability to initiate tumor in vivo compared to CD44− cells (Yamaguchi et al., 1995; Yamaguchi et al., 1996; Okamoto et al., 1998; Ponta et al., 2003; Olsson et al., 2011; Rivera et al., 2011; Zöller, 2011; Asselin-Labat and Filby, 2012; Roudi et al., 2015; Hiraga and Nakamura, 2016; Liou, 2019).