Very little is known about the molecular and genetic mechanisms involved in prostate cancer. Previous studies have shown frequent loss of heterozygosity (40%) at chromosomal regions 8p, 10q, and 16q, suggesting the presence of tumor suppressor genes in these regions. The LNCaP cell line, established from a metastatic lesion of human prostatic adenocarcinoma, carries a t(6;16)(p21;q22) translocation. To determine whether this translocation involved genes important in the process of malignant transformation, we cloned and sequenced the t(6;16) breakpoint of this cell line. Sequence analysis showed that the breakpoint is within the haptoglobin gene cluster on chromosome 16, and that, on chromosome 6, the break occurs within a novel gene, tpc, similar to the prokaryotic S10 ribosomal protein gene. The translocation results in the production of a fusion transcript, tpc/hpr.