It has been reported that ligands of GPCRs, such as prostaglandin (PGE2) and gastrin-releasing peptide (GRP), which are often overexpressed in oral cancer, can activate GPCR and Src-mediated matrix metalloproteinase (MMP), leading to the cleavage and release of EGFR ligands [39]. Here, EGFR is linked to lip and oral cavity carcinoma.