Expression and specific knock-down of heat shock protein 70 (Hsp70) in rheumatoid arthritis (RA) fibroblast-like synoviocytes (FLSs). Hsp70 was expressed in cultured RA FLSs as shown by reverse transcriptase-polymerase chain reaction (a) and Western blotting (b). Hsp70 levels were increased by tumor necrosis factor-alpha (TNF-α) treatment. Gene knock-down was specific for Hsp70; constitutional Hsp70 (Hsc70) levels were unaffected (c). The experiments were performed in RA FLSs from five patients and these are representative figures. GAPDH, glyceraldehyde-3-phosphate dehydrogenase; siRNA, small interfering RNA.