STING1 and neoplasm: In addition, chronic or over-stimulation of STING has been shown to selectively initiate anti-proliferative and pro-apoptotic programs in T cells [111, 129, 157–161], which, combined with the STING/IFN-dependent up-regulation of immune checkpoints, such as IDO1 and PD-L1, in the TME [12, 35, 162–167] may limit the overall anti-tumour potency of the T cell compartment.