PTGS2 and exocrine pancreatic carcinoma: To further investigate the above mechanisms, we applied CXB, UMC, and DMC side-by-side to a pair of pancreatic carcinoma cell lines that had been well characterized previously with regards to their COX-2 status: MIA-PaCa-2 cells are negative for COX-2 expression, whereas Bx-PC-3 cells express high levels of COX-2 [25,26].