A small molecule inhibitor of JAK2 (IC50 = 6 nM) and the related kinases FLT3 (IC50 = 25 nM) and RET (IC50 = 17 nM) with significantly less potent activity against JAK3 (IC50 = 169 nM); inhibits the growth of Ba/F3 cells expressing JAK2V617F or MPLW515L mutations (IC50 = 200 nM).