CD44 and colorectal carcinoma: Although the presence of EpCAMhigh/CD44+ cells correlated with the degree of differentiation, depth of invasion, clinical stage and metastatic status in CRC (Liu et al., 2014a,b) and gastric cancers (Han et al., 2011), because of the plasticity and the not completely known role of their isoforms, CD44 expression does not seem to be an appropriate marker of MetSCs (Hsu et al., 2013; Pitule et al., 2014; Rowehl et al., 2014; Qiu et al., 2015; Nagano and Saya, 2004).