Effect of overexpression of different Jaks, c-Src, or Lyn on the activation of Akt and Stat5.

COS-7 cells were transfected with either the Stat5a cDNA only (lanes 1 and 7) or together with cDNAs encoding the different Jaks (lane 2 to 4), c-Src (lane 5), Syk (lane 6), or Lyn (lane 8). Twenty hours after transfection, cells were serum-starved for 4 hours prior to preparation of whole-cell extracts. (A) Akt phosphorylation was determined by Western blotting using phospho-specific Akt antibody (upper panel). The blot was reprobed with anti-Akt antibody (lower panel). (B) Activation of Stat5a was measured by EMSA using GRR probe.