The effects of Stat5 deficiency on signaling mediated by Jak2V617F in primary hematopoietic cells. BM from control, MxCre;Jak2V617F/+, and MxCre;Jak2V617F/+;Stat5fl/fl mice were factor-deprived for 15 hours. Cell lysates were prepared by direct boiling in 2× sample buffer and subjected to immunoblotting with phospho-specific antibodies against Stat5 or p70S6K, and total antibodies against Stat5, p70S6K, Bcl-xL, Cyclin D2, and Pim1. Erk2 was used as loading control.