PROM1 and cancer: The fact that CD133 is highly expressed in many cancers, plus it was found to be overexpressed in 50% of HCC, pancreatic, and gastric cancer patients (Ferrandina et al., 2009; Schmohl and Vallera, 2016), and highly expressed with poor prognosis, particularly in HCC (Kohga et al., 2010; Yang et al., 2010) have made CD133+ cells an attractive target for immunotherapy using CAR T cells.