Fig. 3

NF-κB rather than STAT6 activation mediated IL-4-induced MUC5AC protein synthesis in BECs. BECs were treated with IL-4 (20 ng/ml) for 3, 6, 12, or 24 h. The complete cell-cultured medium was used as control. Intracellular p-STAT6 and p-P56 proteins were measured by Western blot. (a) Representative image of immunoblots of p-STAT6 and p-P56. (b) Bar graph depicting changes in relative density of p-STAT6 and p-P56 according to a. (c) BECs were pretreated with specific STAT6 inhibitor (AS1517499) or a selective IκB kinase inhibitor (IKK 16) for half an hour, then treated for 24 h in the presence or absence of 20 ng/ml IL-4. Immunofluorescence staining of MUC5AC protein was performed according to the Methods. Representative staining is shown in the c. (d) BECs were treated with 20 ng/ml IL-4 for 24 h in the presence or absence of 50 μM 2-APB. Then cell lysates were used to detect endogenous NF-κB transcriptional activity. Results are expressed as mean ± SD; n = 4 experiments. *P < 0.05 versus normal control, ^# P < 0.05 versus IL-4 treated group