Fig. 1.

TGF-β₂ upregulates arginase activity and arginase I expression in lung epithelial cells. C, control; T, TGF-β₂; Cy, cytomix; Cy + T, cytomix + TGF-β₂. A: TGF-β₂ enhances arginase activity in small airway epithelial cells (SAECs) 24 h after stimulation. Preincubation and addition of TGF-β₂ to cytomix-treated SAECs increases total arginase activity throughout the experiment (n = 8–10). B: TGF-β₂ enhances arginase activity in A549 cells with the same trend as in SAECs (n = 8–10). C: representative Western blots and densitometry analysis (normalized by β-actin) indicates that TGF-β₂ increases arginase 1 (ARG1) protein expression in SAECs (n = 3). Spaces between lane T48 and lane Cy24 and between lane Cy + T24 and lane Cy48 indicate that the data are from 1 Western blot experiment, but not run in the same order as shown in the figure. D: quantitative PCR results demonstrate that TGF-β₂ increases arginase 1 mRNA expression in SAECs. Data are shown as means ± SD. *P < 0.05 compared with control group; ^P < 0.05 compared with cytomix group.