Profiling collagenase gene expression, collagenase activity, and collagenolysis in resorbing cartilage. Bovine nasal cartilage chips were cultured in medium ± interleukin-1 (IL-1) + oncostatin M (OSM) for 14 days exactly as described in the legend to Figure 1. As a measure of collagen, the levels of hydroxyproline (OHPro) released into the media from unstimulated (control) and IL-1+OSM-stimulated cartilage were assayed (n = 3); cumulative OHPro release is shown. Active collagenase activity in the media was assayed using the 3H-acetylated collagen diffuse fibril assay. Aminophenylmercuric acetate (0.67 mM) was used to activate pro-collagenases in order to measure the total collagenase activity (pro + active). RNA was extracted from cartilage, and matrix metalloproteinase (MMP) -1, -13, and -14 gene expression was determined by real-time polymerase chain reaction (n = 3) as described in Materials and methods. The data are presented relative to 18S. Values are the mean ± standard error of the mean. ◇ = control; ▲ = IL-1+OSM.