Overexpression of HTRA1 promoted malignant phenotype of pancreatic tumor cells in vitro and pancreatitis-induced PDAC in KC mice, however, inhibiting HTRA1 blocked cell cycle at the G2/M phase, thereby inhibiting the malignant phenotype of tumor cells and promoting apoptosis in vitro, and inhibited the progression of PDAC in KC mice. Here, HTRA1 is linked to pancreatitis.