In addition, Hpa2 expression was shown to be down-regulated in multiple malignant tissues including head and neck [2,12], gastric [13,14], breast [15], bladder [16], colon [17], and pancreatic carcinomas [18], strongly suggesting that Hpa2 could have a tumor-suppressor function. This evidence concerns the gene HPSE2 and exocrine pancreatic carcinoma.