Fucosyltransferase 1 (fut1) expression was decreased using siRNA against fut1 in rheumatoid arthritis (RA) synovial fibroblasts. Cells were stimulated with TNF-α (25 ng/ml) for 24 hours. (A) Fut1 expression in fut1 siRNA-treated RA synovial fibroblasts and control siRNA-treated RA synovial fibroblasts. (B) RA synovial fibroblasts were first transfected with control or fut1 siRNA, and were grown on the top inserts. Human dermal microvascular endothelial cells (HMVECs) were plated in the bottom of the wells of the transwell system for 24 hours. HMVECs were plated on Matrigel with nontreated, control siRNA-transfected or fut1 siRNA-transfected RA synovial fibroblast-conditioned medium for 6 hours. A representative photograph of HMVECs from co-culture with nontreated, control or fut1 siRNA-transfected RA synovial fibroblasts is shown. Arrows indicate tubes. (C) HMVECs incubated with fut1 siRNA-transfected RA synovial fibroblast conditioned media formed significantly fewer tubes on Matrigel compared with control siRNA-treated RA synovial fibroblasts or nontreated RA synovial fibroblasts. Means are presented with standard error of the mean. *P <0.05 was significant (n = number of RA patient synovial fibroblasts).