FAT1 and cancer: Other genes differentially mutated in HPV-positive versus HPV-negative head and neck squamous cell carcinomas include E2F1, a cell cycle related gene more commonly mutated in HPV-positive cancers (19% versus 2%), and FAT atypical cadherin 1 (FAT1) and ajuba LIM protein (AJUBA), two genes involved in differentiation that are more commonly mutated in HPV-negative cancers (32% versus 3% and 7% versus 0%, respectively) [2].