There are a lot of functions that microfilaments do. The first of them is the organization of the plasma membrane which give shape to surface structures such as microvilli. Microfilaments can exist as a tight bundle of filaments making up the core of the slender, fingerlike microvilli. Microfilaments can function on their own or serve as tracks for ATP-powered myosin motor proteins, which provide a contractile function (as in muscle) along microfilaments. Specialized cells such as macrophages use contractile microfilaments to engulf and internalize pathogens, which are then destroyed internally.
