CD8A and melanoma: For example, IL‐2 released by melanoma cells can promote CD8+ T cell senescence by activating signal transducer and activator of transcription (STAT)5–5‐hydroxytryptophan–aryl hydrocarbon receptor pathway, labeled with enhanced expression of senescence‐related genes in CD8+ T cells (PD‐1), lymphocyte activation gene 3, CD39, Tim‐3, and dysfunctional cytotoxicity (decreased release of IFN‐γ and TNF) [113, 114, 115, 116, 117].