CD44 and cancer: CD133 (also known as prominin-1) is also a transmembrane 5-domain glycoprotein.[12] Previous studies have identified CD133 as a CSC marker related to tumorigenesis and progression in plenty of solid tumors, including colorectal cancer, breast cancer, and gastric cancer.[3] An increasing number of studies are investigating the prognostic and clinicopathological roles of CD44 and CD133 in various types of cancers, including gastric cancer.[3,13]