NOTCH1 and head and neck squamous cell carcinoma: The treatment of NOTCH-mutated HNSCC cell lines with the compound PTC-124 (Ataluren) was demonstrated to re-express the functional NOTCH1 protein and induce the expression levels of Notch-regulated genes such as HES1, HES5, and AJUBA, thus effectively reverting the loss-of-function mutations found in the tumor cells [221].