Fig. 4.

GH and IGF-I synergize in STAT5 activation. A, Serum-starved MIN6 cells were treated with vehicle (−), bGH (500 ng/ml), or IGF-I (20 ng/ml) or cotreated with bGH plus IGF-I (G/I) for 15 min. Cell extracts were analyzed by immunoblotting with anti-pSTAT5 and anti-β-actin, respectively. WB, Western blot. B, Densitometric analysis of pooled data, as in A, from eight independent experiments. Comparison of the level of STAT5 activation induced by bGH and IGF-I cotreatment (referred to as G/I) with that induced by bGH alone (set as 100%) is shown. Data are mean ± sem (n = 8). P < 0.05 (G/I vs. GH).