Besides, in vivo disease reconstitution assay indicated that the secondary Prmt1‐deleted CML mice had much lower leukemia burden (GFP+ cells; Figure S4G, Supporting Information) and prolonged survival (median survival: Prmt1fl/fl vs Prmt1fl/fl; Cre‐ERT2 was 21 days vs not reached after monitoring for 65 days; Figure S4H, Supporting Information). Here, MAPK3 is linked to chronic myelogenous leukemia, BCR-ABL1 positive.