The arthritogenic SF clone B2 exhibits diminished adhesion to proteins of the extracellular matrix. Adhesion assays as described in Materials and methods. Mean averages of triplicates with mean background (adhesion to BSA) values subtracted. Representative experiment out of three. t-test P values were always less than 0.05. BSA = bovine serum albumin; hTNF = human tumor necrosis factor; SF = synovial fibroblast; TAg = large tumor antigen; wt = wild-type.