DAPK1 and head and neck squamous cell carcinoma: Ovchinnikov et al. [55] using methylation-specific polymerase chain reaction (MSP) assay identified a three genes panel, RASSF1A, DAPK1, and CDKN2A genes, with ability to detect tumor presence with an overall accuracy of 81% in the DNA isolated from saliva of HNSCC patients when compared with the DNA isolated from the saliva of healthy nonsmoker controls, proving the application of saliva for assessing the hypermethylation status of tumor-suppressor genes.