Of note, mice with Grm1 or Grm5 melanoma both exhibit tumor formation on the hairless skin, including the pinnae and tails, rather than on trunk areas, as observed for BRAFV600E and NRASQ61K induced melanoma, suggesting that the origin of the transformed cell may not be identical (epidermal vs. hair follicle). The gene discussed is GRM5; the disease is melanoma.