In this context, Ago2, the most abundant Ago protein in somatic cells specifically required for early mouse development, shows specific functions during miRNA processing and cell maturation.58 Here we present evidence that Ago2 protein expression is increased during monocyte differentiation of leukemic myeloid progenitors, whereas it is downregulated during granulocyte differentiation of human leukemic cell lines and freshly isolated blasts from acute promyelocytic leukemia patients. The gene discussed is FBXW7; the disease is acute promyelocytic leukemia.