In prostate cancer, inactivating TP53 mutations are detected at frequencies in the range of 10–20% in primary tumours (IARC TP53 Mutation Database: www.iarc.fr/P53/index.html1), whereas based on the novel findings of Narla et al (2001), tumour-specific KLF6 mutations would be expected overall in up to half of sporadic prostate tumours with Gleason scores in the range of 3–8 (not preselected for loss of heterozygosity status), and thus would constitute the most frequent gene mutation event identified to date in prostate carcinogenesis. The gene discussed is KLF6; the disease is prostate neoplasm.