MMP7 and oral cavity squamous cell carcinoma: It has been reported that SIRT1 is overexpressed in pancreatic cancer tissues and is a promoter of the occurrence and metastasis of pancreatic cancer [44]; however, SIRT1 has the opposite effect in oral squamous cell carcinoma, which inhibits EMT through the SIRT1/Smad4/MMP7 pathway [45].