MEK/ERK-dependent B7-H1 expression in HSCs. (a) B7-H1 mRNA levels in HSCs measured by RT-PCR after exposure to IFN-γ (10 U/mL) for 6 hours with or without 10 μg/mL CHX or 10 μg/mL ActD for 90 minutes. (b) Flow cytometric analysis of B7-H1 expression in control HSCs (without IFN-γ stimulation) and after 24 hours incubation with IFN-γ with or without 1 hour pretreatment with signal transduction inhibitors, that is, 100 μM U0126 (MEK1/2), 100 μM SP600125 (JNK), and 100 μM LY294002 (PI3 K). (c) Western blot analysis of ERK1/2 phosphorylation in HSCs after incubation with IFN-γ (10 U/mL) or 1 ng/mL PMA, with or without 1 hour preincubation with 100 μM U0126. (d) RT-PCR analysis of B7-H1 mRNA levels in HSCs exposed for 24 hours to IFN-γ (10 U/mL) or 1 ng/mL PMA with or without 1 hour pre-incubation with 100 μM U0126.
