Fig. (2) Phosphatase activity of PTP enzymes (PTP1B, 12 mU; Yop, 0.4 U; CD45, 3U) in the presence of test compound NPBD or sodium orthovanadate as a positive inhibitor control. Relative fluorescence units (RFU) are expressed as a percentage of the maximum achieved in each assay for individual enzymes ±SEM.