SOS2 and chronic myelogenous leukemia, BCR-ABL1 positive: We also noticed that the structural histological organization of the spleen was significantly altered as a consequence of the CML development in our control transgenic mice expressing normal levels of both SOS1 and SOS2 (WT (both −TAM and +TAM) and SOS1FL/fl kept in the absence of TAM (Figure 4), which displayed significantly more disorganized and less defined red pulp and white pulp areas within this hematopoietic organ.