SOS1 and chronic myelogenous leukemia, BCR-ABL1 positive: Since, under physiological conditions, SOS1 is known to be expressed in myeloid cells and is regulated by the ABL kinase in the processes of RTK-induced actin cytoskeleton remodeling [32], our observations in SOS1/2-KO mice suggest that SOS1 may be a critical mechanistic contributor to the pathogenesis of CML and thus may constitute a valuable potential therapeutic target for the treatment of this disease.