Genes that have been intensively studied in primary NSCLC include p16 (cyclin-dependent kinase inhibitor 2A), RASSF1A (Ras association domain family protein 1A), APC (adenomatous polyposis coli), RARβ-2 (retinoic acid receptor β), DAPK (death-associated protein kinase) and MGMT (O6-methylguanine DNA methyltransferase). Here, CDKN2A is linked to non-small cell lung carcinoma.