Identification of intact SLRP core proteins and fragments in knee articular cartilage. Presented is identification of intact small leucine-rich proteoglycan (SLRP) core proteins and fragments in age-matched macroscopically normal (N), osteoarthritic (OA) or fibrillated (F) knee articular cartilage (AC). We used affinity-purified anti-carboxyl-terminal SLRP antibodies (PR-84, PR-85, PR-184 and PR-353) and a monoclonal antibody to full-length keratocan core protein (KER-1) to perform Western blotting of samples separated by 4% to 12% Bis-Tris lithium dodecyl sulphate PAGE and blotted to nitrocellulose. All samples were pre-digested with chondroitinase ABC and keratanase-I before electrophoresis. The brackets above the lanes indicate that macroscopically normal and fibrillated articular cartilage were sampled from the same individual nonarthritic joint for this comparison. Extracts from an equivalent wet weight of tissue were loaded in each lane for comparison. The ages of tissue donors are indicated above each lane.