Figure 4

(A) Effect of the general protease inhibitor α₂ macroglobulin at a concentration of 2 U ml⁻¹ on HBL melanoma cell invasion through fibronectin. When added to non-TNF-α-stimulated cells, the invasion was not significantly reduced. In contrast, the increased invasion of the TNF-α-stimulated cells was completely inhibited by α₂ macroglobulin and the invasion of these cells reduced to −8% of the control cell invasion. Results are the mean±s.e.m. of three experiments, ^*P<0.05. (B) Effect of α₂ macroglobulin (2 U ml⁻¹) on the migration of control and TNF-α-stimulated cells. α₂ macroglobulin decreased the control level of migration and the increase in migration resulting from cell exposure to TNF-α was completely inhibited by the protease inhibitor (n=3, ^*P<0.05).