Intermediate filaments (IFs), in concert with microfilaments (MFs) and microtubules (MTs), form the cytoskeleton, and each of these fibrillar networks exhibits rather unique structural and functional characteristics. Intermediate filaments were discovered in eukaryotic cells in the late 1960s, and their name comes from the fact that their diameter is intermediate between MFs and MTs. In contrast to the latter, IFs constitute a network that extends from the nuclear envelope throughout the cytoplasm, and in many cases, interact with cell surface domains involved in cell-cell and cell- matrix...