NOTCH1 and head and neck squamous cell carcinoma: We compared HNSCC cell line models (Table 2) with demonstrable evidence of high basal activation of NOTCH1 by immunoblotting (n = 5) (Table 2) to cell lines with documented homozygous inactivating NOTCH1 mutations (n = 6) to examine if RNA expression of any HES/HEY family members were reliable biomarkers of chronic NOTCH1 signaling.