Figure 3
Summary of in vitro angiostatin generation by plasminogen activators and D-penicillamine. Murine serum was incubated for 0, 2, 4.5 or 20 hours with D-penicillamine and tPA (a and b) or uPA (c and d). Conversion of plasminogen to plasmin (a and c) and plasmin to angiostatin (b and d) were scored separately on a semi-quantitative scale. Note concentration dependent conversion of plasminogen to plasmin (a), and conversion of plasmin to angiostatin (b) with increasing concentrations of tPA and D-penicillamine (b). Surprisingly, uPA was very efficient in plasmin generation (c), while with increasing uPA concentrations a reciprocal effect on angiostatin formation was observed (d). tPA concentrations (μg/ml): 
: 0.08; 
0.4; 
: 2; 
: 4; 
: 20 and 100 uPA concentrations (units/ml): 
: 0.004; 
: 0.02; 
: 0.1.