Dose dependence of the effect of rhIL-6 on plasminogen mRNA expression in primary murine hepatocytes. (A) Primary hepatocytes were grown in serum-free EMEM supplemented with 0.1% BSA for 24 hours, followed by incubation with increasing concentrations of rhIL-6 for 24 hours in serum free EMEM supplemented with 0.1% BSA. Total RNA was isolated and Northern blot analysis was performed as in Fig 1. Migration of RNA molecular size standards is shown on the left side of the panel. (B) Fold-stimulation of plasminogen mRNA levels was determined as the ratio of plasminogen/cyclophilin hybridization band intensity determined by laser densitometric scanning of the autoradiogram in (A). The ratio was normalized to one for untreated cells.