CDKN2A and neoplasm: Two high-risk genes have been identified: the cell cycle regulator CDKN2A on chromosomal band 9p21 (Hussussian et al, 1994) and the cyclin-dependent kinase-4 (CDK4) on chromosomal band 12p14 (Zuo et al, 1996), the products of which are known to be components of potent tumour-suppression pathway.