Although tumors can arise from ESA+CD44+ALDH− cells taken from the UM-C6, OMP-C5 and OMP-C8 tumor lines [30], an ALDH+ subset of TG ESA+CD44+ cells does exist in all xenogeneic colorectal tumor lines investigated to date (n = 6). This evidence concerns the gene EPCAM and colorectal neoplasm.