Abstract
By SDS/PAGE analysis we have observed that human synovial cell monolayers secrete a prominent 39kDa protein which could not be detected in skin and lung fibroblast. This protein was purified to homogeneity by heparin-Sepharose chromatography and reverse-phase h.p.l.c. The N-terminal sequence was found to be almost identical to that of a recently described bovine protein detected in the mammary secretions during the involutionary phase of the lactational cycle. Characterization of this 39 kDa protein may provide a useful marker for classification of connective tissue cells.