In the present study, we demonstrated that cordycepin could significantly inhibit FGF9-induced MA-10 cell tumorigenesis in vitro and in vivo by the suppression of MAPK and Rb/E2F1 pathways, and the downregulation of cell cycle proteins and FGFRs, implying that cordycepin may be used as a new drug for testicular cancer therapy. The gene discussed is FGF9; the disease is testicular cancer.