PROM1 and neoplasm: As deficient MMR is generally reported to occur more commonly in right-sided CRC (Yearsley et al., 2006; Iacopetta, Grieu & Amanuel, 2010; Benedix et al., 2012; Koi, Tseng-Rogenski & Carethers, 2018), the study was also designed to stratify the CRC cases according to location of the tumor, to determine if CD133 expression is associated with tumor side.