Pervanadate: So much more than a protein tyrosine phosphatase inhibitor

The chemical reagent pervanadate is widely used to study phosphotyrosine signaling because it is a potent, irreversible inhibitor of protein tyrosine phosphatases that globally increases tyrosine phosphorylation across the proteome. In this issue of <i>Science Signaling</i>, Mulholland <i>et al.</i> show that pervanadate also modulates phosphotyrosine signaling by oxidizing specific cysteine residues on the tyrosine kinase SRC, thereby leading to hyperactivation of this ubiquitous signaling enzyme.