Immunoblot analysis of the specificity of the reaction of patients’ sera against PSMA. LNCaP lysate or recombinant PSMA were run on SDS-PAGE, transferred onto polyvinylidene fluoride (PVDF) membrane, and incubated either with a positive patient’s serum or with the same serum after it had been preincubated with recombinant PSMA (120 µg/ml). Mr, molecular weight markers; lane 1, LNCaP lysate treated with positive serum (dilution 1:50); lane 2, LNCaP lysate treated with the same serum (dilution 1:50) after preincubation with recombinant PSMA (120 µg/ml); lane 3, recombinant PSMA treated with positive serum (dilution 1:50); lane 4, recombinant PSMA reacted with the same serum (dilution 1:50) after preincubation with recombinant PSMA (120 µg/ml); lane 5, LNCaP lysate treated with serum from a healthy male donor, diluted 1:50; lane 6, recombinant PSMA treated with serum from a healthy male donor, diluted 1:50. Lastly all blots were treated with antihuman IgG labeled with AP.