FIGURE 8.

Matriptase proteolysis mediates tyrosine phosphorylation and binding of Src and PKCδ to 70 kDa CDCP1. A, anti-phosphotyrosine Western blot analysis of proteins immunoprecipitated from 22Rv1 cell lysates using a rabbit anti-CDCP1 antibody (CST 4115). Lysates were collected from 22Rv1 cells either untreated (−) or treated (+) with 20 nm matriptase for the indicated times. The blot was reprobed with an anti-rabbit secondary antibody to detect rabbit IgG to assess consistency in the amount of antibody used for immunoprecipitations. B, photographic images of 22Rv1 cells either untreated (left panel) or treated for 2 h with 20 nm matriptase (right panel). Bar, 50 μm. C, anti-phosphotyrosine, -PKCδ, -Src, and -CDCP1 (CST 4115) Western blot analysis of anti-CDCP1 (CST 4115) immunoprecipitates obtained from 22Rv1 cells either untreated (−) or treated (+) with matriptase (20 nm; 0.5 h). Lysates were collected in the presence (+) or absence (−) of sodium vanadate and sodium fluoride. All experiments included control immunoprecipitations performed with species matched IgG. NS, nonspecific.