TM4SF1 and familial pancreatic carcinoma: To further validate that TM4SF1 mediated pancreatic cancer cell migration and invasion by regulating DDR1, we increased the expression of DDR1 in TM4SF1 silenced cells and then observed the protein expression levels of TM4SF1 and DDR1 and the abilities of cell migration and invasion by western blot and Transwell assay.