Figure 7.
Blocking autocrine TGF-β signalling renders PANC-1 cells resistant towards the growth-suppressive effect of Rac1 inhibition. (A) PANC-1 cells were transfected with Rac1 or control (Co) siRNA as outlined in the legend to figure 1. Fourty-eight hours later cells were treated with PP1 (10 μM) or vehicle for 24 h and subjected to [3H]-thymidine incorporation assay. Data represent the mean ± standard deviation from six wells processed in parallel. **, p < 0.01; ***, p < 0.001; n.s., not significant. (B) PANC-1 cells were transiently cotransfected with FLAG-tagged Smad2 and a MYC-tagged version of ca Rac1 (Q61L) as indicated over the figure. 24 h after transfection cells were stimulated or not with TGF-β1 for 1 h in the absence or presence of 10 μM PP1. Following lysis and anti-FLAG and anti-MYC IPs, samples were analysed by sequential immunoblotting for phospho- (p-) and total (t-) Smad2 as well as Rac1.