FIGURE 5.

The CDCP1 ectodomain is shed intact from the cell surface. Western blot analyses using a goat antibody generated against the extracellular domain of CDCP1 (R&D Systems AF2666). A, analysis of lysates from prostate cell lines passaged with EDTA demonstrating that this antibody recognizes 135 kDa but not 70 kDa CDCP1 indicating that the cognate antigen is located in the shed portion of CDCP1. B, analysis of conditioned media from these cell lines. Cells were cultured in serum-free medium for 3 days. The medium was then centrifuged briefly to remove intact cells, and proteins were recovered by acetone precipitation. C, analysis of serum-free conditioned media from HeLa cells transiently transfected with expression constructs encoding CDCP1 truncated after either Arg-368 (designated R368*) or Lys-369 (K370*).