To validate the high expression of CD133 in hESCs, we assessed CD133 expression by qPCR using two paired primers (different loci at the cDNA of PROM1) in six human cell lines, including two hESC lines (WA26 and RuES2), a colon adenocarcinoma cell line (HCT116), an osteosarcoma cell line (U2OS), a cervix adenocarcinoma cell line (HeLa), and a human embryonic fibroblast (HEF) cell line (Fig. 1a). The gene discussed is PROM1; the disease is osteosarcoma.