Thus, to fully understand the role of PTMs in PD-L1 regulation, more studies are needed to (1) characterize the types of PTMs of PD-L1, (2) decode the modification sites and the functional consequences of PTMs, (3) clarify the interactions among these PTMs, (4) evaluate the availability of PD-L1 PTMs as potential targets in PD-1/PD-L1 axis for cancer treatment. Here, PDCD1 is linked to cancer.