Identification of PTP-MEG2 by immunodepletion. Combined Mono-Q column fractions (nos. 40-43; Figure 1B) obtained with membrane extracts of day-6 PV ECFCs were incubated with purified anti-PTP-MEG2 or irrelevant rabbit immunoglobulin G (IgG) bound to protein A-agarose for 4 hours at 4°C. PTP activity in the untreated control and treated supernatant samples were then determined. Data represent relative activity obtained with 3 different samples.