Stable expression of PTP1BΔ6 modulates JAK/STAT signaling and proliferation. (A-B) Immunoblot analysis of WCE from (A) L-428 cells or (B) U-HO1 stably expressing PTP1B_WT, PTP1B_C215S, and PTP1BΔ6 or control cells (EV) using the indicated antibodies. (C) PTP1B phosphatase activity in the different L-428 cell clones determined by a PTP1B phosphatase assay. Significances are calculated in comparison with the empty vector values. *P ≤ .05; **P ≤ .01; ***P ≤ .001. (D) Electrophoretic mobility shift assay to determine STAT DNA binding activity with WCE from L428 cells expressing ectopic PTP1B_WT, PTP1B_C215S, PTP1BΔ6, or L-428 control cells (EV). (E) Supershift analysis of WCE from untreated L-428 control cells using no antibody (lane 1), a NF-κB p50-specific antibody (lane 2, negative control), or an anti-STAT6 specific antibody (lane 3). (F) STAT6 luciferase reporter activity in L-428 cells stably expressing PTP1B_WT, PTP1B_C215S, and PTP1BΔ6 and in L-428 control cells (EV). Mean values and SEM are depicted. Significances are calculated in comparison with the empty vector values. *P ≤ .05; **P ≤ .01; ***P ≤ .001. (G) BCL6 mRNA expression levels in the different L-428 cell clones determined by qRT-PCR analysis. Mean values and SEM are depicted. Significances are calculated in comparison with the empty vector values. *P ≤ .05; **P ≤ .01; ***P ≤ .001. (H-I) Proliferation of the different stable L-428 (H) or U-HO1 (I) cell clones determined by MTS assay. Mean values and SEM are depicted. Significances are calculated in comparison with the empty vector values. *P ≤ .05; **P ≤ .01; ***P ≤ .001.