In addition, the elastase-tva;Trp53flox/flox;Ptf1aCre/+ mice were crossed to Ink4a/Arfflox/+ (Krimpenfort et al., 2001) mice to assess tumor development in the context of a simultaneous p53 deficiency and Ink4a/Arf single allele deletion. The gene discussed is CDKN2A; the disease is neoplasm.