TNF and rheumatoid arthritis: The transwell assay and tube formation test demonstrated significant upregulation in the migration and capillary-like structure formation of HDMECs, respectively, under the treatment of supernatants from RA-FLS and HDMEC co-culture after TNF-α induction when compared with those from co-culture without TNF-α induction; and the migration and tube formation were significantly decreased in the circHIPK3 knockdown RA-FLS co-culture group whether TNF-α induction was performed or not (Figures 1F,G,I).