Figure 4.

SP-C BRICHOS mutants upregulate activating protein 1 (AP1) and c-Jun N-terminal kinase (JNK) activation. A549 and HEK293 cells were transiently transfected in the absence (Mock) or presence of the indicated EGFP–SP-C constructs, and harvested 48 hours after transfection. Ultraviolet light (UV) treatment (40 mJ/cm²) was used for a positive control sample. Cell lysates were analyzed for phospho–c-Jun (A and B), phospho–SAPK/JNK, and total SAPK/JNK expression, using monoclonal antibodies (C and D). An anti–β-actin antibody was used as a loading control. Band intensities were quantified by densitometry, and the ratio of either c-Jun to β-actin or phospho-JNK to total JNK was determined. Data are expressed as fold change over WT control, and represent the mean ± SD of three separate experiments. Representative immunoblots appear above each graph. *P < 0.05 versus WT control. ⁺P < 0.001 versus WT control.