Cytoskeleton

1. Microfilament (actin): G-actin monomer; F-actin helix; + end polymerization, need ATP; - end depolymerization; motility, contractile ring in mitosis, microvilli.
2. Intermediate filament (tissue specific): Type I: keratin, epithelial; Type II: desmin, muscle, vimentin, fibroblasts, blood vessel SM, endothelial, glial fibrillary acidic protein, glial cell, peripherin, axon; Type III, neurofilament; Type IV, neuclear envelop lamin. Alzheimer's disease, cirrhotic liver diseases.
3. Microtubule: transport contents; cilia, flagella, mitotic spindle, dynein, ATP; dynein retrograde, kinesin anterograde. Gout, colchicine. Vinblastine, vincristine, cancer.

Microfilament and microtubule are continuously assembly and disassembly. Intermediate filaments are stable.