SOS2 and chronic myelogenous leukemia, BCR-ABL1 positive: These crosses gave rise to mice with different genotypic combinations that, upon appropriate TAM treatment for SOS1 ablation, allowed us to monitor and compare the evolution of p210BCR/ABL-induced CML in the littermates of appropriate and relevant SOS genotypes, including WT, SOS1-KO, SOS2-KO, or SOS1/2-DKO mice (Figure 1).