Microarray approaches have identified three prostate tissue and cancer-prostate-specific genes: p503S, a 241-amino acid protein that encodes human tetraspan NET-1, a member of the tetraspanin/TM4SF family, involved in cancer metastasis) [1], P504S, also referred to as the AMACR gene, encodes human α-methylacyl-CoA racemase, a 382-amino acid protein involved in the conversion of R-stereoisomers of branched-chain fatty acids to S-stereoisomers [2-6] and p510S, identified as the human ABC transporter MOAT-B [7]. The gene discussed is TSPAN1; the disease is cancer.