CD8A and cancer: After activated, CD8+ T cells infiltrate into tumors, and eliminate cancer cells expressing neoantigens by releasing INF-γ, perforin, and granzyme B. These processes need to be accompanied by specific signals (e.g., inflammatory cytokines including TNF-α, IFN-γ, and IL-1; other cytokines including IL-2 and IL-12), which overcome peripheral tolerance provided from immune suppressive cells, such as regulatory T (Treg) cells, myeloid-derived suppressor cells (MDSCs), tumor associated macrophages (TAMs) in tumor milieu.