Fig. 4.

The PRLR antagonist, G129R, fails to block GH-induced STAT5 tyrosine phosphorylation in T47D-ShPRLR cells. Serum-starved T47D or T47D-ShPRLR cells were treated with vehicle, PRL (A and C), or GH (B and D) (500 ng/ml each; 15 min) in the presence or absence of G120R (A and B) or G129R (C and D) (5-fold molar excess of antagonist compared with PRL or GH). The detergent cell extracts were resolved by SDS-PAGE and serially immunoblotted with anti-pSTAT5 and anti-STAT5. The data shown are representative of three independent experiments. WB, Western blot; pSTAT5, phosphorylated STAT5.