Figure 1.

PRN473 is a potent inhibitor of Fpr1‐induced Btk phosphorylation in neutrophils. (A) Neutrophils were stimulated with fMLP, in the presence or absence of PRN473 at the indicated concentrations, for 1 min, after which lysates were prepared, and Btk was immunoprecipitated and probed on Western blots with the phosphotyrosine‐specific antibody (4G10). Total Btk is absent in Btk‐deficient animals. Tubulin was used as a loading control. (B) Representative Western blots of neutrophils stimulated with fMLP probed for phospho‐Src (Tyr416), phospho‐p38 MAPK, total p38 MAPK, phospho‐Akt (p‐Akt) and total Akt, following treatment with different concentrations of PRN473 as indicated. (C, D) Densities of phospho‐proteins relative to total protein [4G10 to tubulin (C), p‐Src to p38 (D), p‐p38 to p38 (E) and p‐Akt to Akt (F)]; data shown are means ± SEM; n = 5.