RA-FLSs can express a series of B cell nutrients such as B lymphocyte stimulator and vascular cell adhesion molecule-1 in enhancing intercellular adhesion (106), while overexpression of hypoxia-inducible factor-1α (HIF-1α) promotes the upregulation of the cell contact mediator IL-15 on the RA-FLS surface (107), resulting in prolonged B cell survival and a reduced apoptosis rate. This evidence concerns the gene IL15 and rheumatoid arthritis.