Figure 4.
Retinoic acid (RA) enhances the interferon-β (IFN-β)-induced STAT-1 expression and phosphorylation. THP-1 cells were pretreated with RA (10−8 m) for 16 hr, and then IFN-β (2·5 U/ml) was added to cells for the times indicated. (a) Time–course of total STAT-1 protein accumulation induced by IFN-β and RA (a Western blot analysis using anti-STAT-1 antibody and then assessed by densitometry). (b) Cells were treated with IFN-β (0·5 or 2·5 U/ml) for 2 hr after 16 hr RA pretreatment. Phosphorylated STAT-1 protein was detected by Western blot analysis (anti-PY701 antibody and densitometric analysis).