CSF1R and pancreatic ductal adenocarcinoma: Inhibition of CSF1R signaling in a mouse model of pancreatic ductal adenocarcinoma can enhance antigen presentation function of macrophages and anti-tumor T cell responses, but these tumor-reactive T cells have PD-1, the expression of PD-1 and other immune checkpoint molecules is increased, which weakens the anti-tumor effect of CSF1R inhibitors.