Biotinylated fluorophosphonate (FP-biotin) labelling of fibroblast activation protein alpha (FAPα) on chondrocyte membranes. Membrane extracts isolated from IL-1 plus oncostatin M stimulated chondrocytes were treated with or without FP-biotin. Labelled proteinases were isolated using streptavidin-agarose beads and eluted with reducing SDS-PAGE loading buffer. Proteins were separated by SDS-PAGE and stained with colloidal Coomassie. The 97 kDa protein was identified by mass spectrometry to be FAPα.