All chimeras were expressed and purified as follows, based on the WT PTP1B protocol. The cells were thawed on ice and resuspended in 10X their equivalent volume of a lysis buffer, consisting of 50 mM imidazole pH 7.5, 1 mM EDTA, 3 mM DTT, and 10% glycerol with one crushed protease-inhibitor tablet for every 50 mL of solution. The cells were lysed by sonication at 60% power for 10 pulses then mixed on ice for 1 minute and repeated 4-6 times until completely lysed. The cell lysate was centrifuged at 4°C at 29000 g for 30 minutes. The supernatant was filtered with a 0.45-micron syringe filter.