As a result of their down-regulated expression, the tumor suppressor genes encoding p16INK4a (cyclin-dependent kinase inhibitor 2A), RASSF1A (RAS association domain family 1 isoform A), and p16INK4b (RAS association domain family 1 isoform B) may play a significant role in tumorigenesis. The gene discussed is CDKN2A; the disease is neoplasm.