CD8A and cancer: The diverse activity of tumor-infiltrating lymphocytes (TILs) may play a significant role in the progression of many types of cancers, as an increased presence of cytotoxic CD8+ TILs (CTC) has often been associated with improved overall survival [22], whereas an increased frequency of immunosuppressive CD4+ regulatory T cells (Treg) in the TME correlates with poorer prognosis [23].