DNA-based ratiometric Nitric Oxide sensitive probe. It can target the plasma membrane, the trans-golgi network, endosome, lysosome, or phagosome and is applicable in-vitro, intracellularly, in mouse microglia, or zebrafish brain. It is relevant to cancer, sepsis and trauma, autoimmune disease and vascular disease, among others. In this figure (Jani et al., Nat. Chem. Biol., 2020), NOckout reported subcellular simultaneous NO dynamics in the plasma membrane of cancer cells.