CD8+ T cells infiltrating the RCC TME frequently exhibit high expression of inhibitory checkpoint receptors—including programmed death-1 (PD-1), cytotoxic T-lymphocyte-associated protein 4 (CTLA-4), and T cell immunoglobulin and mucin domain-containing protein 3 (Tim-3)—alongside low levels of proliferative markers such as Ki-67, suggesting a state of dysfunction and exhaustion (13, 14). The gene discussed is CTLA4; the disease is renal cell carcinoma.