miR-28 is induced by JAK2 V617F, MPL W515 mutants, Bcr/Abl and STAT5 1*6. Ba/F3 cell lines expressing indicated proteins were tested for miR-28 relative expression. (A) JAK2 V617F human TpoR-Ba/F3 cells selected for autonomous growth were treated with the JAK2 inhibitors: AG490 (10μM); JAK Inhibitor I (0.5μM); AZD1480 (3μM), TG101209 (3μM) or vehicle only (-) for 24 hours (*P < .05; **P < .001). Absence of toxicity was demonstrated by Trypan blue staining. (B) Ba/F3 cells expressing the indicated human TpoR mutants, Bcr/Abl or STAT5 1*6 were selected for autonomous growth in absence of cytokines and tested for miR-28 expression (*P < .0001). (C) The indicated cell lines were electroporated either with an empty expression vector expressing the CD2 surface marker (pREX-CD2), or the same bicistronic expression vector coexpressing the STAT5DN (dominant negative) mutant with the CD2 surface marker. Electroporation levels were verified by FACS and the miR-28 expression was quantified by stem-loop qRT-PCR. The presented results are representative of 3 indpendent experiments.