Additional pairs with a strong preference for tumor-to-tumor signaling in primary lesions include CNTN4-PTPRG, EFNA2-EPHA5, FGF6-FGFR4, FGF9-FGFR4, GDF11-ACVR2B, and INHBC-ACVR2B. This evidence concerns the gene FGF6 and neoplasm.