Mono-methylated arginine (MMA) is well-known inhibitor of inducible nitric oxide synthase (iNOS) and has been extensively used for studying NO’s mechanistic roles during macrophage activation, cardiovascular diseases, hypercholesterolemia, nervous system disorders, lung diseases, autoimmunity, and viral/bacterial infections, including tuberculosis (7, 73–76). Here, NOS2 is linked to tuberculosis.