cDNA microarray analysis was used to describe a gene, &agr;-methylacyl-CoA racemase (AMACR), whose expression is consistently upregulated in clinical prostate cancer versus benign prostate. Immunohistochemical staining using high density tissue microarrays demonstrated that primary and metastatic prostate carcinomas showed AMACR protein overexpression. The absence of AMACR staining in most normal tissues, coupled with its enzymatic activity, makes AMACR an excellent candidate for the development of molecular probes for the non-invasive imaging of prostate cancer and as a potential drug target. For details, see the article by Luo et al. p. 2220 of this issue.