Using single-cell sequencing, Guo et al. identified a variety of CD8+ T-cell functional subsets via multiple transcriptional markers, such as PD-1, CD103 and Tim3, in NSCLC, and demonstrated that a high ratio of predysfunctional to dysfunctional T cells correlated with better prognosis in 11 patients with adenocarcinoma [19]. The gene discussed is CD8A; the disease is non-small cell lung carcinoma.