Interestingly, using a novel real-time single-cell nanochip, we recently reported that the killing kinetics of human tumour-specific CD4 T cells are delayed compared to those of CD8 T cells, suggesting that CD4 CTLs might rely on a distinct killing mechanism and/or spatiotemporal localization of TCR-pMHC interactions to acquire cytotoxic functions compared to conventional cytolytic lymphocytes (73). The gene discussed is CD8A; the disease is neoplasm.