Differential secretion of PAI-1 and CTGF in hepatocytes. Western blot analysis of medium samples, which were collected just before cell lysate was prepared. Hepatocytes were seeded in 90 mm2 petri dishes with a density of 5–6 × 106 cells/well. Before cytokine and hormone stimulation cells medium was changed (5 ml DMEM without FCS and without phenol red). Thereafter, cells were treated and harvested by and by as indicated and 40 μg protein was applied to each lane. After stimulation PAI-1 protein increased during incubation time (1 to 4 h) and was rapidly secreted. CTGF was up-regulated and strong expressed in hepatocytes after co-stimulation with TGF-β and dexamethasone. In a time-frame of four hours no CTGF signal could be detected. The time-dependent induction of CTGF was analysed densitometrically.