Fig. 7. Characterization of integrin binding by GFAP and vimentin in the peripheral nerve, and of ERK1/2 phosphorylation. (A) Rat sciatic nerve lysate was immunoprecipitated with anti-GFAP or anti-vimentin antibody. The immunoprecipitated proteins were separated in SDS-PAGE (7.5%) under reducing conditions and blotted with antibodies against integrin subunits v, ß8, 5 and ß1. GFAP co-precipitated with the integrin subunits v and ß8 but not ß1, whereas vimentin co-precipitated with the integrin subunits 5 and ß1 but not v. (B) Sciatic nerve lysate of GFAP-null mice was immunoprecipitated as described above with anti-vimentin antibody and blotted with anti-integrin v antibody; similarly the wild-type sciatic nerve lysate was immunoprecipitated with anti-GFAP antibody and blotted with anti-integrin v antibody. Vimentin still did not co-precipitate with integrin v in GFAP-null mice lysate, whereas integrin v again co-precipitated with GFAP in lysate of control-mice nerves. (C) Protein extracts form the distal stamp of wild-type mice treated with DMSO and wild-type mice treated with the MEK inhibitor PD098059 at 3 days (T3) after injury were immunoblotted with antibody against total ERK1/2 or phosphorylated ERK1/2. By densitometry the ratio of totalERK1/2 to pERK1/2 was measured and is stated below the blot as a number, indicates the phosphorylation state. Mice treated with PD098059 showed reduced ERK phosphorylation (D) Protein extracts from the distal stump of crushed nerves from wild-type and GFAP-null mice at T3 and T6 were immunoblotted with antibody against total ERK1/2 or phosphorylated ERK1/2. By densitometry, the ratio of totalERK1/2 to pERK1/2 was measured as described above. Nerves of GFAP-null mice showed less phosphorylated Erk1/2 compared with controls at both time points after injury.