PD-L1 is a checkpoint regulator in immune cells, it is expressed on immune or non-hematopoietic cells. Expression of the protein is seen during pregnancy where it has a role in suppressing the immune system. PD-L1 induces an inhibitory signal in activated T-cells and promotes T-cell apoptosis. It is overexpressed in a number of different cancers where it is believed to play a significant role in the cancer s ability to evade the immune system.
