PDCD1 and colorectal carcinoma: We have determined that CRC cell-intrinsic PD-1 inhibits tumor progression by knocking down and overexpressing PDCD1. To further explore the role of clinical drug targeting PD-1 on the genetic manipulation of PD-1, we firstly treated SW480 cells with nivolumab antibody targeting PD-1 to block the tumor cell-intrinsic PD-1 for 48h.