Western blot analysis of MMP-12 secretion by ASMC. Cells were incubated for 48 hours with 10 ng/ml IL-1β or TNF-α alone, or IL-1β combination with TNF-α, PD98059 (1 μM), SP600125 (10 μM) or wortmannin (250 nM) for 48 hours. MMP-12 protein released into conditioned media was determined by Western blot using 20 μl of 40-fold concentrated samples. Relevant band intensities were quantified by scanning densitometric analysis and normalized to 5 × 105 cells. Results are the mean ± SEM from three ASMC donors. **P < 0.01 compared with control; +P < 0.05, +P < 0.01 compared with IL-1β alone.