Consistent with our Q61R results, mice transplanted with Rab27bfl/fl LSKs expressing NRASG12D mostly developed MML, while those transplanted with Rab27b-deficient LSKs expressing NRASG12D had reduced incidence of CMML and instead died of T-ALL (Table 2), as evidenced by flow cytometric analysis (Figure 6B) and the histology of the bone marrow and spleen (Figure 6C and Supplemental Figure 8B). This evidence concerns the gene RAB27B and acute lymphoblastic leukemia.