Figure 7.

CLPA toxicity requires dual‐protease activation. (a) HeLa cells, which do not express uPA, exhibiting 50% confluence were incubated for 6 h with serial dilutions of PA variants (0–10 nM) and FP59 at 1.9 nM. Following incubation, the medium was replaced and cell viability was measured using an MTT assay after 48 h. (b) PA variant toxicity to LLC cells was assessed in the presence or absence of MMP inhibitors, GM6001 and TIMP‐2. Both inhibitors, GM6001 at 40 μM and tissue inhibitor of metalloproteinases TIMP‐2 at 20 μM, significantly reduced toxicity of CLPA variants as compared to the untreated control. In (a) and (b) results were averaged across three experiments containing four replicates of each sample.