Previously, we found that treatment of cells with the Hsp90 inhibitor 
geldanamycin (GA) leads to a substantial reduction in the number of processing 
bodies (P-bodies), and also alters the size and subcellular localization of 
stress granules. These findings imply that the chaperone activity of Hsp90 is 
involved in the formation of P-bodies and stress granules. To verify these 
observations, we examined whether another Hsp90 inhibitor radicicol (RA) 
affected P-bodies and stress granules. Treatment with RA reduced the level of 
the Hsp90 client protein Argonaute 2 and the number of P-bodies. Although stress 
granules still assembled in RA-treated cells upon heat shock, they were smaller 
and more dispersed in the cytoplasm than those in untreated cells. Furthermore 
eIF4E and eIF4E-transporter were dissociated selectively from stress granules in 
RA-treated cells. These observations were comparable to those obtained upon 
treatment with GA in our previous work. Thus, we conclude that abrogation of the 
chaperone activity of Hsp90 affects P-body formation and the integrity of stress 
granules.