Another gene showing promoter hypermethylation in pulmonary carcinoids is CDKN2B, coding for a cyclin-dependent kinase inhibitor p15Ink4b which is functionally similar to the tumor-suppressor gene CDKN2A (encoding for the p16INK4a protein), but less well characterized in its tumorigenic potential. The gene discussed is CDKN2A; the disease is neoplasm.