CD44 and cancer: PDAC cells enriched with CD44, and/or CD24 and/or CD133 (Hermann et al., 2007; Li et al., 2007; Hong et al., 2009; Ding et al., 2012; Salaria et al., 2015) are highly tumorigenic-resistant to conventional anti-cancer therapy, and have been used as cancer stemness markers (Ercan et al., 2017).