Fig. 3. Downregulation of vimentin in C2C12 myotubes and biochemically differentiated cells. (A) Disappearance of vimentin filaments during terminal differentiation. Phase-contrast images (a,c) and corresponding immunofluorescent images detecting vimentin (b,d) in C2C12 myoblasts (a,b) and myotubes (c,d). (B) A decrease in vimentin (a) and an increase in desmin (b) during terminal differentiation detected by immunoblotting. (C) Disappearance of vimentin filaments in biochemically differentiated mononucleated cells. Phase-contrast images (a,c) and corresponding immunofluorescent images detecting vimentin (b,d) of sodium butyrate-treated (a,b) or DMSO-treated (c,d) C2C12 cells. Cells were treated as described for Fig. 2B. Arrows indicate a biochemically differentiated cell, which has a invaginated nucleus and a markedly reduced number of vimentin filaments (c,d). Bar, 20 µm.