STAT5B and chronic myelogenous leukemia, BCR-ABL1 positive: We extended our studies of the effects of S5-DBD-PA mediated Stat5 inhibition to leukemic cells and compared the influences of Stat5 inhibition in Bcr-Abl expressing human K562 CML cells and in human erythroid leukemia HEL cells, positive for the Jak2(V617F) point mutation.