Profiling metalloproteinase inhibitor gene expression and inhibitory activity in resorbing cartilage. Bovine nasal cartilage chips were cultured in medium ± IL-1+OSM for 14 days exactly as described in the legend to Figure 1. RNA was extracted from cartilage, and TIMP-1, -2, -3, and -4, RECK, and α2M gene expression determined by real-time polymerase chain reaction (n = 3) as described in Materials and methods. The data are presented relative to 18S. Inhibitory activity was assayed in the culture media by the addition of samples to a known amount of active matrix metalloproteinase-1 (MMP-1) in the diffuse fibril assay (n = 3). Values are the mean ± standard error of the mean. ◇ = control; ▲ = IL-1+OSM. *p < 0.05 using the Student's t test. α2M, alpha 2 macroglobulin; IL-1, interleukin-1; OSM, oncostatin M; RECK, reversion-inducing cysteine-rich protein with Kazal motifs; TIMP, tissue inhibitor of metalloproteinase.