ABCA1 and rheumatoid arthritis: To further validate our results, ABCA1 mRNA was examined by RT-qPCR.After exposure to thrombin (1, 2 or 4 U/ml), levels of ABCA1 mRNA (Fig. 6B) in RA-VSMCs were suppressed in a dose-dependent manner.To verify the effect of thrombin on foam cell formation, the RA-VSMCs were induced by ox-LDL (50 μg/ml).