Fig. 8. Tyrosine phosphorylation of PlexA1 by Fes and inhibition by NP-1 co-expression. (A) Expression in COS-7 cells. COS-7 cells were transfected with the indicated expression vectors, and total cell lysates were immunoblotted with anti-PlexA1, anti-NP-1 or anti-Fes Ab. (B) Tyrosine phosphorylation of PlexA1 by Fes. Each lysate was immunoprecipitated with anti-HA Ab. The immunoprecipitates were immunoblotted with anti-phosphotyrosine or anti-HA Ab. (C) Sema3A enhances tyrosine phosphorylation of PlexA1 by Fes. COS-7 cells expressing HA-PlexA1/NP-1 or Fes/HA-PlexA1/NP-1 were stimulated with or without 5 U/ml Sema3A for 10 min, and cell lysates were immunoprecipitated with anti-HA Ab, and then immunoblotted with 4G10 or anti-HA Ab.