Expression of a single gene can convert cells lining the seminal vesicle in the pelvis into prostate cells, a new study shows. The results provide a better understanding of the molecular mechanisms controlling the development of seminal vesicle and prostate tissues, which could provide valuable insights as to why cancer arises frequently in the latter but only rarely in seminal vesicles. Previous studies have found that loss of the gene Nkx3.1 results in impaired prostate differentiation in mice, prompting Aditya Dutta et al. to study the gene in greater detail. First, they confirmed that lack of Nkx3.1 in prostate cells results in reduced expression of a number of genes associated with prostate differentiation. The researchers then infected seminal vesicle epithelial cells with a virus expressing Nkx3.1, finding that inducing expression of this gene caused the seminal vesicle epithelium to convert into a prostate-like state in terms of structure, histological appearance and genetic markers. Further investigation in human prostate cells identified several components of the regulatory network involved in this "tissue respecification" process, including certain histone-modifying enzymes. The authors suggest that further exploration of this network could help researchers understand the tissue-specificity of prostate cancer.