In vivo investigations were conducted using the Grm1-Tg transgenic mouse strain that develops spontaneous metastatic melanoma, which was crossed with SELENOK−/− mice to generate the following littermates: Grm1-Tg/SELENOK−/−, Grm1-Tg/SELENOK−/+, Grm1-Tg/SELENOK+/+. The gene discussed is GRM1; the disease is metastatic melanoma.