CD274 and cancer: As an important immune checkpoint, high expression of PD-L1 is detected in various immune cells and cancer cells, and PD-L1 can be transported into the nucleus and then participates in regulating gene transcription, which is involved in interferon signaling [18,26], NF-kB signaling [19,27,28], immune checkpoints [19,22,23,29,30,31], and inflammation [31,32,33].