Phosphorylation of EGF-R, Flk-1 and ERK1/2 and induction of Egr-1 protein after intraperitoneal injections of VEGF and EGF.

Mice received intraperitoneal injections of VEGF (A), EGF (B), or normal saline (A, B). Tissues were processed at 5 minutes, 10 minutes, or both for Western blot analysis of phosphorylated Flk-1 (P-Flk), EGF-R (P-EGFR), and ERK1/2 (P-ERK), as described in “Materials and methods.” Levels of phosphorylated ERK1/2 are compared with total ERK2 (total ERK), whereas levels of phosphorylated receptor are compared to IgG. A lower band that appears in some lanes of the P-EGF-R blot is nonspecific. Tissues were harvested from growth factor-treated mice at 1 hour, 2 hours, and 4 hours and were processed for Western blot analyses of Egr-1 in the heart (H), lung (L), brain (B), kidney (K), liver (Li), spleen (S), and skeletal muscle (SK). +, growth factor-treated mice; −, normal saline-treated mice.