PTP activity of purified CD148 molecule. Affinity purified CD148 molecule was incubated with a tyrosine phosphorylated syntethic peptide (TSTEPQpYQPGENL). The amount of free phosphate released as inorganic phosphate in the absence or presence of vanadate was measured by the Malachite Green Phosphatase Assay (UBI) and it is shown as nmol/L concentration. Affinity purified CD50 molecule was used as a negative control.