CDKN2A and oral cavity squamous cell carcinoma: There are a number of studies which have utilized the use of cell cycle regulatory genes such as P16INK4a, p21WAF1, and p27Kip1 in predicting the behavior of certain cancers such as malignant astrocytomas [23], oral squamous cell carcinomas [24], vulval carcinomas [25], and primary large-cell neuroendocrine carcinoma of the parotid gland [26].