LNCaP and PC3 cells were obtained from the American Type Culture Collection (Manassas, VA). The Ace-1 and Leo cell lines were available from Dr. Rosol's laboratory at The Ohio State University (Columbus, OH) [11 (link),12 (link)]. Mouse monoclonal antibodies 3C6 and 4D8 were obtained from Northwest Biotherapeutics (Seattle, WA). All other chemicals and cell-culture reagents were purchased from Fisher Scientific (Somerville, NJ), Pierce (Rockford, IL), Invitrogen (Grand Island, NY), or Sigma-Aldrich (St. Louis, MO). The PSMA inhibitors CTT-54 and FAMXCTT-54 (Fig. 1) were available from prior studies [17 (link),19 (link)].