Loss of the melanoma tumour suppressor INK4A (CDKN2A – HUGO Gene Nomenclature Committee) leads to rapid melanoma formation in activated N-RAS-expressing mice and, in a remarkable genetic experiment, it was shown that the loss of one allele of Sox10 is sufficient to counteract activated N-RAS hyperpigmentation and melanoma (Shakhova et al., 2012). The gene discussed is CDKN2A; the disease is melanoma.