Conversely, in NSCLC, intrinsic PD-1 exhibited an antitumor role by downregulating signaling pathways such as PI3K/AKT and MAPK/ERK1/2, and its silencing or antibody blockade resulted in accelerated proliferation via PI3K and MAPK pathway activation in both NSCLC and colon cancer cells [144,145]. Here, PDCD1 is linked to non-small cell lung carcinoma.