HTRA1 and pancreatic ductal adenocarcinoma: Pancreatitis is a crucial risk factor for pancreatic ductal adenocarcinoma (PDAC), and our previous study had proved high-temperature requirement protein A1 (HTRA1) exacerbates pancreatitis insult; however, the function and mechanism of HTRA1 in pancreatitis-initiated PDAC is still unclear.