However, on the basis of the present demonstration that IGFBP6 is chemotactic for RA T lymphocytes in vitro and that the majority of T cells infiltrating RA synovium displayed very strong immunopositivity for IGFBP6, it is tempting to speculate that the main pathogenic roles exerted by IGFBP6 in RA may be that of T-cell chemoattractant from bloodstream to synovial membrane. The gene discussed is IGFBP6; the disease is rheumatoid arthritis.