Fig. 5From: Current status of skin cancers with a focus on immunology and immunotherapyAnt- PD-1 mechanism of action.Programmed cell death protein 1 (PD-1) is an immune checkpoint and causes apoptosis of antigen-specific T-cells in lymph nodes and reduces apoptosis in regulatory T cells. PD-1 inhibitors block PD-1 and activate the immune system to attack tumorsBack to article page