NOTCH1 and head and neck squamous cell carcinoma: According to a 2015 TCGA analysis, NOTCH1-3 is inactivated in 17% HPV+ and 26% HPV- HNSCC.138 The majority of these aberrations are found in NOTCH1, including nonsense mutations causing truncated proteins, missense mutations within functional regions, and frameshift deletions and insertions.