With CD8+ cytotoxic and CD4+ helper T cells playing a central role in anti-tumor immunity, several PCTS-based studies have focused on understanding the localization and function of tumor infiltrating lymphocytes (TILs) in solid tumors, including lung, breast and melanoma [27,37,38,39,40,41,42,43,44,45,46,47]. The gene discussed is CD4; the disease is neoplasm.