Fig. 7. Dominant negative Rap1 (RapN17) or Rap1GAP impairs neurite outgrowth and sustained ERK activation (A,B) (a) TGW cells (A) or TGW(Dok-4) cells (B) were transfected with GFP, GFP-RapGAP (SPA-1) or GFP-RapN17 and incubated for 48 hours with or without GDNF. (b) Mean of the longest neurite was determined for each culture from measurements of 50 neurons for three different experiments. Each data point represents the mean ± s.e.m. (C) TGW(Dok-4) cells were transfected with GFP, GFP-RapGAP (SPA-1) or GFP-RapN17, serum-starved, and stimulated with GDNF (50 ng/ml) for the indicated times, and cell extracts subjected to western blot analysis with the anti-ERK or anti-phosphoERK antibody.