Antigen-specific IgG can be detected in the sera of other patients with prostate cancer. A schematic layout of the antigen-encoding phages (panel A) and data from three separate subjects with prostate cancer (panels B-D) are shown. "POS IgG" indicates a positive control phage encoding human IgG, and "NEG" indicates a negative control phage not encoding an immunoreactive protein. The arrows point to the immunoreactive proteins identified.