GZMB and cancer: An excellent example was recently reported by the team of Rao, who designed G-SNAT as a GzmB-activatable self-assembly smart probe for the assessment of cytotoxic T lymphocyte-mediated cancer cell killing.109 G-SNAT incorporated a 2-cyanopyrimidine group in close proximity to a GzmB-responsive IEFD peptide so that intramolecular cyclization occurred after (1) GzmB cleavage and (2) reduction of the disulfide bond by intracellular glutathione (Fig. 5a).