For example, we recently validated saliva matrix metalloproteinase 1 (MMP-1) as a strong diagnostic marker of oral cavity cancer in saliva samples from a large cohort (n = 1160), supporting previous reports that this protein is one of the most promising salivary biomarkers for oral cavity cancer using a targeted MS-based assay to compare multiple candidate proteins [66,68]. Here, MMP1 is linked to oral cavity cancer.