Effect of PTP1BΔ6 on JAK/STAT signaling. (A) Schematic representation of the different PTP1B variants used in this study. CD, catalytical domain; PRD, proline-rich domain; ER-T, endoplasmic reticulum targeting domain. (B) Luciferase assay for the readout of STAT1 activity with and without (control) stimulation with IFNγ. HEK293 cells where transfected with empty vector pFLAG (EV) as a control, PTP1B WT, PTP1B_C215S (C215S), and PTP1BΔ6 (Δ6) encoding vectors. Mean values and standard error of mean (SEM) are depicted. Significances are calculated in comparison with the empty vector values. *P ≤ .05; **P ≤ .01; ***P ≤ .001. (C) Cytoplasmic and nuclear extracts from HEK293 cells transfected with EV, PTP1B_WT, PTP1B_C215S, or PTP1BΔ6 either left unstimulated (−) or stimulated (+) with IFNγ were subjected to immunoblot analyses, using antibodies specific for pSTAT1, STAT1, PTP1B, and β-actin as a loading control. (D) Luciferase assay for STAT6 activity with and without (control) stimulation with IL-4. HEK293-ST6 cells were transiently transfected either with pFLAG-CMV2 (EV) or with PTP1B_WT, PTP1B_C215S, or PTP1BΔ6 vectors. Mean values and SEM are depicted. Significances are calculated in comparison with the empty vector values. *P ≤ .05; **P ≤ .01; ***P ≤ .001. (E) Cytoplasmic and nuclear extracts from HEK293-ST6 cells transfected with EV, PTP1B_WT, PTP1B_C215S, or PTP1BΔ6 either left unstimulated (−) or stimulated (+) with IL-4 were subjected to western blot analyses, using antibodies specific for pSTAT1, STAT1, PTP1B, and β-actin as a loading control.