SF3B1 and B-cell chronic lymphocytic leukemia: To define the role of Sf3b1-K700E in the activation of mTORC1 and MYC pathways, we first identified splice variants associated with DM CLL cells as well as Sf3b1-K700E B cells through RNA splicing analysis using the rMATS pipeline (24) (Figure 4, A and B, and Supplemental Figure 3D).