BVT 948 is a noncompetitive, cell-permeable inhibitor of protein tyrosine phosphatases (PTP; IC50s = 0.09-1.7 μM). It facilitates the oxidation of the catalytic cysteine residue by hydrogen peroxide. Similarly, it inhibits redox-sensitive cytochrome P450 (CYP) isoforms, including CYP2C19 and CYP2D6, with IC50 values less than 10 μM. BVT 948 also inhibits the protein methyltransferases SETD8, SETD2, G9a, SMYD2, CARM1, and PRMT3 with IC50 values from 0.7 to 3.2 μm. Presumably through its effects on PTPs, BVT 948 enhances insulin signaling in cells and insulin tolerance in ob/ob mice, suppresses the expression of matrix metalloproteinase-9 and invasion in breast cancer cells, and increases NMDA-induced substance P release by spinal cord slices.