IGF1R and acute lymphoblastic leukemia: While some ALL and AML cell lines express insulin and IGF‐1 receptors (IGF‐1R) [29, 30, 31], almost all of APL cell lines such as HL‐60, NB4, and PL‐21 express abundant IGF‐1R protein and proliferate with IGF and IGF analogs stimulation and their growth and basal DNA synthesis decrease with monoclonal antibodies directed against the IGF‐1R and other IGF antagonists [32, 33, 34].