STI-571 inhibits LPS-dependent phosphorylation of c-kit in APCs. PEMs were treated with either LPS (5 μg/mL), STI-571 (10 μM), LPS + STI-571, or left untreated (None) for 24 hours. Then, whole cell lysates were obtained and Western blot and immunoprecipitation studies were performed as indicated in “Materials and methods.” Western blot (WB) and IP studies were repeated 3 times with similar results.