CD99 and acute myeloid leukemia: Despite these difficulties, a great number of cell surface markers have been identified that are upregulated on CD34+CD38- LSCs compared with normal CD34+CD38- HSPCs, for example, it has been revealed that CD90 and CD117 are deficient in acute myeloid leukemia (AML) LSCs, while CD123, TIM3, CD47, CD96, CLL-1, and IL-1 receptor accessory protein (IL1RAP), G protein-coupled receptor 56 (GPR56), CD93, CD44 and CD99 are highly expressed in AML LSCs.