Figure 7.
mGBP-2 inhibits PDGF activation of Rac. (A) Control transfectants or mGBP-2–expressing cells were serum starved for 2 h and treated with PDGF (10 ng/ml) for 5 min, harvested, and analyzed for the levels of active Rac. Western analysis of TCLs for Rac confirmed that reduced levels of active Rac are not the consequence of reduced total Rac. (B) Western blots from PBD pull-downs were quantified, and the results are expressed as described in Materials and Methods (*p < 0.05 compared with PDGF-treated control transfectants; n = 4). (C) Treatment with IFN-γ inhibits Rac activation by PDGF. NIH 3T3 cells were serum starved for 18 h in the presence or absence of IFN-γ (500 U/ml), treated with PDGF (10 ng/ml) for 5 min, harvested, and analyzed for the levels of active Rac. The Rac-PAK PBD/GST complexes were analyzed by Western blotting for Rac. Western analysis of TCLs for Rac confirmed that reduced levels of active Rac are not the consequence of reduced total Rac. (D) Western blots from PBD pull-downs were quantified and the results expressed as described in Figure 5 (*p < 0.05 compared with PDGF-treated cells that did not receive IFN [control]; n = 4). (E) NIH 3T3 cells were treated with 500 U/ml IFN-γ for 16 h and/or 10 ng/ml PDGF for 5 min. Cell lysates (20 μg) were analyzed for mGBP-2 expression by Western blot. The membrane was reprobed with actin to verify equal loading.