Fig. 2. Co-localization of HSF1 and HSF2 in stress granules. (A) HSF1 and HSF2 co-localize to the stress granules upon heat shock (HS). Monoclonal antibodies against HSF1 were used to detect endogenous HSF1 and polyclonal HSF2 antibodies to detect endogenous HSF2 by double staining of HeLa cells analyzed by immunofluorescence microscopy. (B) The epitope-tagged HSF1 and HSF2 constructs were transiently transfected into HeLa cells. Anti-Myc antibody was used to detect the ectopic HSFs (green) and polyclonal antibodies against HSF1 and HSF2 were used to detect endogenous HSFs (red). Yellow indicates co-localization in the merged image (Merge). Scale bars, 5 µm.