Many techniques have been used in an attempt to distinguish odontogenic cysts (including KCOT) from ameloblastomas (especially unicystic type), which include demonstration of cell surface carbohydrates with blood group specificity; determination of alkaline phosphatase activity in the stroma; distribution of lectins and involucrin in the epithelium; characterization of cytokeratin profiles; counting of AgNORs and quantification of cell proliferation markers such as PCNA and Ki67. The gene discussed is PCNA; the disease is odontogenic cyst.