NOS3 and cancer: 4T1 cancer cell orthotopic implantation increased plasma concentration of endogenous inhibitor of endothelial nitric oxide synthase (eNOS), asymmetric dimethyl L‐arginine (ADMA; Figure 2A) that is highly released from activated endothelial cells.23 Other metabolites such as symmetric dimethyl L‐arginine (SDMA) (Figure 2B) and N‐monomethyl L‐arginine (L‐NMMA) (Figure 2C) that are produced to a lesser extend or do not inhibit eNOS remained unchanged.