MCF-7 cells were cultured in RPMI/5% (v/v) fetal calf serum for 48 h, then treated with 10 nM uPA, uPA–PAI-1, uPA–PAI-1 plus RAP (200 nM), uPA–PAI-1R76E, uPA–PAI-2 or vehicle in RPMI containing 300 μg/ml glutamine, 5 μg/ml transferrin and 38 nM selenium. After culturing for 36 h, cell growth was determined using the MTS [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium] assay. Values of cell proliferation are relative to the proliferation of control cells (i.e. vehicle only). (means±S.E.M., n=6, *P<0.05).