Expression of 15-LOX-1 and 15-LOX-2 in human OA cartilage. Representative immunostaining of human osteoarthritis (OA) cartilage for (a) 15-LOX-1 and (d) 15-LOX-2. (b, e) Higher magnification views of the area indicated within the broken line rectangle in panels a and d, respectively. (c, f) Cartilage treated with nonimmune control IgG at the same concentration as the primary antibody (control for staining specificity). (Magnification: ×100 for panels a, c, d and f; ×250 for panels b and e). The results are representative of four separate experiments performed with cartilage samples from four different donors. LOX, lipoxygenase.