Fig. 1.

Characterization of murine lung fibroblasts. A: vimentin and pan-cytokeratin expression by murine lung fibroblasts from matrix metalloproteinase (MMP)-9-deficient mice. After isolation from murine lung, cells were stained for vimentin and pan-cytokeratin (see materials and methods). Human bronchial epithelial cells (HBEC) were used as positive control for pan-cytokeratin staining. Data presented are one representative of three separate experiments. WT, wild type; KO, knockout. B: gelatin zymography. Fibroblasts were cultured in 3-dimensional (3D) collagen gels for 5 days in the presence or absence of cytokines [10 ng/ml tumor necrosis factor (TNF)-α and 5 ng/ml IL-1β]. Media in which the collagen gels were suspended were harvested after 5 days, and gelatin zymography was performed. Media from HT1080 cells, which secrete copious amounts of human MMP-9, which has an apparent molecular size of 90 kDa, and MMP-2, are included as a positive control. Data presented are one representative of three experiments.