Both approaches, BAC mapping and loss of heterozygosity, point to alterations on canine chromosome 11, in the region equivalent to human chromosome 9p21 which is commonly deleted in human tumours [10] and contains the genes CDKN2B and CDKN2A. The first codes for the protein p15INK4B, while the second codes for p16INK4A and p14ARF which are proteins derived from alternate exon 1 sequences and use different reading frames for the common exon 2 [11,12]. The gene discussed is CDKN2A; the disease is neoplasm.