Melanoma onset was similar for HP (median: 136 d post-UV), HPN1 (147 d) and HPN2 (113 d) mice (Supplementary Table 3), but was markedly earlier than seen previously in HGF mice (~200 d).6 The three strains exhibited small differences in the number of primary melanomas/mouse (HP > HPN1 = HPN2), rates of growth for the largest primary melanoma (HPN2 > HP) and final combined tumour volume (HPN2 > HP). The gene discussed is HP; the disease is melanoma.