Glomerular expression of osteopontin in biopsies of human crescentic glomerulonephritis (N = 25), IgA nephropathy with crescents (N = 2), and diffuse proliferative lupus glomerulonephropathy with crescents (N = 1) was studied by immunohistochemistry, in situ hybridization, and combined immunohistochemistry/in situ hybridization.