TABLE 3.

Effect of protease inhibitors on DPPIV activity on IL-1-stimulated fibroblasts^a

Inhibitor	Concn	% Inhibitionb
Diprotin A	1 mM	88.2
PMSF	1 mM	42.9
	0.5 mM	26.9
Bestatin	1 mM	5.1
Aprotinin	10 μg/ml	<1
Pepstatin	10 μg/ml	<1
Leupeptin	20 μg/ml	<1
1,10-Phenanthroline	1 mM	<1
EDTA	5 mM	7.6

^aConfluent HGF (donor, FE) were stimulated with 10 ng of IL-1α per ml for 6 days in 96-well plates and then washed with PBS three times, and confluent-monolayer cells were examined by DPPIV assay in the presence or absence of the indicated inhibitors. 

^bPercent inhibition was calculated as [(DPPIV activity on IL-1-stimulated HGF in the absence of inhibitor) − (DPPIV activity on IL-1-stimulated HGF in the presence of inhibitor)]/(DPPIV activity on IL-1-stimulated HGF in the absence of inhibitor) × 100. DPPIV activities of fibroblasts stimulated with or without IL-1α were 33.4 and 9.3 nmol/60 min/culture, respectively. The results are representative of three different experiments with three different donors (FE, NIK, and MH-12).