Figure 4

PTPRR effect on growth factor-induced ERK signaling. A) PC12 cells stably expressing PTPPBSγ show reduced transient ERK1/2 activity. Serum-starved pools of mock-transduced, PTPBR7 expressing or PTPPBSγ expressing cells were treated with 100 ng/ml EGF for 2 or 5 min before being lysed. Proteins were size-separated and immunoblotted. Representative images of phospho-ERK1/2 (upper panel) and total ERK1 (lower panel) immunoreactivity are depicted. B) Reduced transient ERK activity in PTPPBSγ expressing cells. Quantitative representation of relative phospho-ERK1/2 levels in cells stimulated with EGF for two or five minutes. Results are presented as mean values ± SEM from six independent experiments (Student's t-test, *p < 0.008). C) Increased PTPRR levels have no effect on NGF-induced ERK1/2 activity. Serum starved PC12 cell pools stably expressing PTPBR7 or PTPPBSγ were stimulated with 50 ng/ml NGF for the indicated time points (in min). Cells were then lysed and phospho-ERK1/2 were analysed on Western blots as in panels A-B. Results are the mean ± SEM of three independent experiments.