To test this hypothesis, we selected Fbxo47, which encodes an F-box domain-containing protein of unknown function that has been linked with specific cancers in humans.31 We generated a germ cell-specific Fbxo47-knockout mouse line by crossing Fbxo47-floxed mice with Stra8-GFPCre mice (Supplementary information, Fig. S21c).32 We found that male mice deficient in Fbxo47 were completely infertile. The gene discussed is STRA8; the disease is cancer.