Figure 4.

Airway administration of α₁-antitrypsin (A1AT) protein activates protein tyrosine phosphatase 1B (PTP1B) and protein phosphatase 2A (PP2A) in mice. FVB/NJ and Ptp1b^−/− mice were administered either 2 μM of albumin or A1AT intranasally. (A) PP2A and PTP1B activity levels and (B) PP2A_C phosphorylation at Tyr site 307 was examined in mouse lungs. Densitometry analysis was performed for p-PP2A_C(Tyr307) phosphorylation. (C) Neutrophils from Ptp1b^−/− mice were undergoing cell death at a faster rate than wild-type (WT) neutrophils. Graphs represent mean ± SEM of three measurements from each animal (n = 10 per group). P values shown, comparing both treatments connected by a line. DU = densitometry units.