CD44 and acute myeloid leukemia: To this end, we chose the antigen CD123 out of several cell surface antigens preferentially expressed on AML LSCs compared with normal hematopoietic stem cells, including CD123, CD44, CLL-1, CD47 [7], and T cell immunoglobulin mucin-3 (TIM-3) [27], the rationale of its selection being its overexpression not only by the bulk AML population, but also by LSCs in 75%–89% of AML patients [28-30].