TNF and rheumatoid arthritis: When TNF-α treatment was absent, the HDMECs migration and tube formation decreased significantly with management of supernatants from RA-FLS and HDMECs co-culture under treatment of As2O3 at doses of 1.0 μM and 2.0 μM compared to vehicle control group (p < 0.05, Figure 3C-3D, Supplementary Figure 3A-B).