In tumour microenvironments with elevated TGFβ levels, decreased numbers and limited anti-tumour cytolytic activity of cytotoxic T-cells have been observed, through mechanisms that include induction of T-cell apoptosis (Thomas and Massagué, 2005; Flavell et al., 2010; Liu et al., 2018). The gene discussed is TGFB1; the disease is neoplasm.