FUT1 and rheumatoid arthritis: We found that RA synovial fibroblasts transfected with fut1 siRNA showed less proliferation in response to LPS at 4 and 24 hours (Figure 5D).] As shown in Figure 5D, fut1 siRNA-transfected LPS-stimulated RA synovial fibroblast cultures displayed significantly less proliferation at 4 and 24 hours compared to LPS-stimulated control siRNA-transfected or nontreated RA synovial fibroblasts.