CDKN2A and neoplasm: The tissue-specific, inducible nature (tet-on) of the β-Catenin oncogene combined with Cre-Lox alteration of the p53 tumor suppressor gene led to the development of invasive gastrointestinal adenocarcinomas; though some chimeras developed lymphomas and sarcomas due to the heterozygous mutations of p53 and Ink4a present in the ES cells.