Post-translational processing generates 70 kDa CDCP1 from the full-length 135 kDa protein. A, Western blot analysis using a goat antibody generated against the last 13 C-terminal residues of CDCP1 (Abcam ab1377) was performed on lysates from the indicated cell lines passaged with EDTA. B, trypsin induces the generation of 70 kDa CDCP1. Lysates from prostate cancer PC3 cells passaged with EDTA and 22Rv1 cells treated once with either EDTA or trypsin (5 min) were examined by Western blot analysis using a goat anti-CDCP1 antibody (Abcam ab1377). C, prostate cancer PC3 and 22Rv1 cells were transiently transfected with a CDCP1-Flag expression construct, and lysates were collected at the indicated time points for anti-Flag Western blot analysis. D, Western blot analysis of lysates from 22Rv1 (left panel) and HeLa-CDCP1-Flag (right panel) cells either untreated or cultured for 24 h in PC3 cell-conditioned medium. Lysates from 22Rv1 cells were probed with a goat anti-CDCP1 antibody (Abcam ab1377) and lysates from HeLa-CDCP1-Flag cells were probed with a rabbit anti-Flag antibody. Anti-GAPDH Western blot analysis was performed to examine protein loading.