MT1-MMP fibrinolytic activity is increased in human monocytes attached to FN, VCAM-1, or ICAM-1. (Top) Proteolytic activity of MT1-MMP was analyzed in cell extracts from monocytes attached to plates coated with 0.5% BSA, 20 μg/mL FN, 10 μg/mL FN fragments H89 and FN80, or 10 μg/mL VCAM-1 or ICAM-1 for 16 hours by fibrinogen zymography. LPS (10 ng/mL) stimulation for 16 hours was included as a positive control. The main 60 kDa fibrinolytic band observed corresponds to the mature form of MT1-MMP. (Bottom) The arithmetic means and SD of the fold induction of MT1-MMP fibrinolytic activity estimated by densitometry are represented (an arbitrary value of 1 was assigned to the MT1-MMP activity in monocytes attached to BSA). n = 3. ^***P < .01.