CDKN2A and neoplasm: In addition, inactivation of the cyclin-dependent kinase inhibitor 2A (CDKN2A) locus, point mutations in tumour protein p53 (TP53) and mutations or deletions of SMAD (Sma/mothers against decapentaplegic) family member 4 (SMAD4) are commonly found in PDAC tumours (see Box 1) (Hruban et al., 2001b).