Figure 2. Representative Northern hybridization of matrix metalloproteinase (MMP), tissue inhibitor of matrix metalloproteinase 1 (TIMP 1), and cyclooxygenase 2 (COX 2) expression by normal equine chondrocytes in monolayer culture stimulated with recombinant equine interleukin-1β (reIL-1) or recombinant human interleukin-1β (rhIL-1). Total RNA (4 μg) was resolved on formaldehyde agarose gels. Blots were probed with a digoxigenin-labeled DNA probes. Treatments: lane 1: control; lane 2: 10 ng/mL rhIL-1β; lane 3: 1 ng/mL reIL-1β; lane 4: 10 ng/mL reIL-1β; lane 5: 100 ng/mL reIL-1β; lane 6: 10 ng/mL reIL-1β + 10⁻⁵ M dexamethasone.