The actin cytoskeleton is a biopolymer network that provides a scaffold for the structural rigidity of cells . Virtually all mammalian cells contain six isoforms of actin, which share 95-99% homology, making actin one of the most evolutionarily conserved proteins in the animal kingdom . Actin is essential for a wide range of mechanical functions, including locomotion , shape change , cell division , force exertion , mechanosensing , and tension homeostasis . Actin protein monomers can polymerize into double-helical filaments , and these filaments are further organized into a variety of suprafilamentous structures (Figure ), such as bundles , crosslinked filament networks , bundle networks , and aggregates .