Inverse correlation between STAT5 activation and differentiation. Ba/F3 cells bearing the indicated receptors were washed 3 times in PBS, starved for 6 hours in RPMI, and then stimulated with the indicated growth factor for 10 minutes. Nuclear extracts were obtained as described. Electrophoretic mobility shift assays (EMSA) were performed using a β-casein probe.33 Competition with unlabeled oligonucleotides were done with either the β-casein probe S or an unrelated nonspecific oligonucleotide (NS). Migration of the specific complex is shown with an arrow. (A) EMSA with nuclear extracts from wild-type Ba/F3 cells, Ba/F3-EpoR, and Ba/F3 E/β treated as indicated above each lane. (B) EMSA with nuclear extracts from Ba/F3-GMR-α and Ba/F3-GMα/βIL3 cells.
(C) EMSA with nuclear extracts from Ba/F3-IL-5Rα and Ba/F3-IL-5α/βIL3 cells. (D) EMSA were performed as in (A), in the absence or presence (+) of specific anti-STAT5 (αSTAT5) or anti-STAT6 (αSTAT6) antisera.
