Key to Cytoskeletal Functions (1)Structure and Support (2)Intracellular Transport 3Contractility and Motility 4Spatial Organization Actin filaments (1) Actin filaments (1) (3) Motor protein Intermediate Microtubule filament Intermediate filaments Nerve cell (b) Motor protein Actin filaments Microtubule (4) 2 Microtubule Motor protein ) (a) Epithelial cell (c) Dividing cell Copyright 1999 John Wiley and Sons.Inc.All rights reserved.The three types of protein