CDX2 and acute monocytic leukemia: Here, we report that turning on human CDX2 expression in the hematopoietic lineage of mice induces acute monoblastic leukemia, through inhibition of the lymphocytic lineage and accumulation of immature monoblasts mediated by the stimulation of the BMP and activin membrane‐bound inhibitor that blocked transforming growth factor‐β‐dependent differentiation of monocytes.