PDCD1 and cancer: The significantly enriched GO terms of tumor CD8+ T cells included ‘cell cycle’, ‘T cell activation’, ‘NF‐κB signaling pathway’, ‘PD‐L1 expression and PD‐1 checkpoint pathway in cancer’, ‘response to interferon‐gamma’, ‘apoptosis’ [44], ‘antigen processing and presentation’ (Fig. 4A), showing divergent functional specialization.