Fig. 3. Immunofluorescence microscopy of C2C12 cells expressing GFP-myosin (green channel in A,D,G) after fixation and staining (red channel) with either an Hsp90 antibody (B,E) or an Hsc70 antibody (H). In cells expressing GFP-myosin the filamentous and globular early intermediates co-localize with Hsp90, and Hsc70. The GFP-myosin assembled in striated myofibrils does not co-localize with either Hsp90 or Hsc70 (inset is an enlargement of the boxed regions in G-I showing a small region of a striated myofibril). Most uninfected cells show diffuse staining of Hsp90 and Hsc70 in the cytosol. In addition, anti-Hsp90 and anti-Hsc70 staining reveals structures similar to the early myosin intermediates in an uninfected population of cells that lack GFP-myosin (e.g. the cell marked by an arrow in E and F). In the color merge panels (C,F,I) the structures in which Hsp90 and Hsc70 (red) co-localize with GFP-myosin (green) are yellow.