(2) In vitro, (Polymerization) both ends of the mf grow, but the plus end faster than the minus Because actin monomers tend to add to a filament's plus end and leave from its minus end----Tread-milling 8900(2) In vitro, (Polymerization) both ends of the MF grow, but the plus end faster than the minus. Because actin monomers tend to add to a filament’s plus end and leave from its minus end---- “Tread-milling