PDCD1 and cancer: CD274 was commonly expressed on normal cells and immune cells, while PDCD1LG2 mainly expressed on antigen-presenting cells; they bind with programmed cell death protein-1 (PD-1) on T cell surface playing important roles in suppression of T-cell immunity and are, accordingly, important targets for blockade-based immunotherapy in cancer (Yearley et al., 2017; Wang et al., 2019).