NAMPT and head and neck squamous cell carcinoma: Considering that Notch1 acts as an oncogene and as a tumor suppressor in human cancer, it will be interesting to investigate whether visfatin also promotes Notch1 expression in other types of cancer, including skin cancer, hepatocellular carcinoma, and head and neck squamous cell carcinoma, in which Notch1 functions as a tumor suppressor.