CDKN2A and head and neck squamous cell carcinoma: Examples of deleted genes in the canine tumors (Fig 2A) include cell cycle gene CDKN2A, one of the best known gene deletions in human HNSCC [1,2,6]; and protein phosphatase PTPRD and cadherin superfamily membrane FAT1, tumor suppressors [51,52] that are also frequently deleted in human HNSCC [1].