The STAT5 - miR-21 - PDCD4 pathway was conserved in CML primary CD34+ cells, and to some extent in acute myeloid leukemia (AML) models as well; the known functions of miR-21 and PDCD4 suggest that their regulation by BCR-ABL1 could participate in the antileukemic response triggered by tyrosine kinase inhibitors. The gene discussed is STAT5B; the disease is acute myeloid leukemia.