PGC and melanoma: PGC expression is markedly upregulated in various cancers, including prostate, breast, endometrial, ovarian, pancreatic, renal, and bladder cancer and eyelid basal cell carcinoma, melanoma, and squamous cell carcinoma, whereas it is either down-regulated or the serum pepsinogen II level is lower in gastric cancer than in healthy controls, which is due to the invasion of large tumors into the stomach body with high numbers of chief cells [3, 10–12].