Mice deficient in Batf do not produce Th17 cells.<h4>Methods</h4>In this study, we aimed to characterize the role of Batf-dependent Th17 cells in prostate cancer by crossbreeding Batf knockout mice with mice conditionally mutant for Pten.<h4>Results</h4>We found that Batf knockout mice had changes in the morphology of prostate epithelial cells compared with normal mice, and Batf knockout mice deficient in Pten (called Batf-) had smaller prostate size and developed fewer invasive prostate adenocarcinomas than Pten-deficient mice with Batf expression (called Batf+). The gene discussed is BATF; the disease is Familial prostate cancer.