MAP4 is not required for plectin binding to microtubules (MTs). Electron microscopy of control human 356 fibroblasts (CIL:23051, this image) and MAP4 immunodepleted (CIL:23052) cells after staining with antibody to NH 2 terminus of MAP4. Cells were microinjected with an antibody to the COOH-terminal domain of MAP4 to remove MAP4 from MTs. 10-nm gold particles decorate MTs in control cells, but are absent in injected cells. Plectin forms bridges between intermediate filaments and MTs in both cells. Electron microscopy of cytoskeletons was performed as described (Svitkina et al., 1995). Briefly, cells on coverslips were lysed as for light microscopy, treated, with recombinant gelsolin NHz-terminal domain, fixed with glutaraldehyde, tannic acid and uranyl acetate, critical point dried, and coated with platinum and carbon. Image corresponds to Fig 9c in J Cell Biol. 1996 Nov;135(4):991-1007.