Specific T cell clusters in the breast cancer TME of all subtypes [21,29] show differential expression for predysfunctional markers (e.g., TCF7), "transitional markers" (e.g., GZMK, IL7R, and PD-1) and late dysfunctional markers (PD-1, CTLA-4, TIM3, and LAG3). The gene discussed is CTLA4; the disease is breast cancer.