MTAP and oral cavity squamous cell carcinoma: Many solid tumors lack or display reduced expression of the enzyme methylthioadenosine phosphorylase (MTAP), including melanomas [10], sarcomas [11,12], pancreatic cancer tumors [13,14], biliary tract tumors [15], lung tumors [16,17,18], and breast cancer tumors [19], as well as oral squamous-cell carcinoma [20], hepatocellular carcinoma [21], and endometrial carcinoma [22].