Treatment with l-Nω-methylarginine (l-NMA, NOS inhibitor) and N-acetyl cysteine (NAC, an antioxidant that also inhibits S-nitrosylation) inhibited endothelial VCAM-1 cell surface expression, VCAM-1-S-nitrosylation, tumor cell transmigration through the endothelium and metastasis formation. Here, VCAM1 is linked to neoplasm.