Recently, CD133 has been reported to be overexpressed in several solid tumors including retinoblastoma (Hemmati et al., 2003), glioblastoma (Singh et al., 2003; Singh et al., 2004), prostate adenocarcinoma (Collins et al., 2005; Rizzo et al., 2005), kidney carcinoma (Florek et al., 2005), pancreatic cancer (Hermann et al., 2007) and colorectal cancers (O’Brien et al., 2007). Here, PROM1 is linked to colorectal cancer.