Final answer:
Microfilaments provide the structural support for microvilli and are involved in muscle cell contraction.
Step-by-step explanation:
The cytoskeletal proteins that provide the structural support for microvilli are microfilaments.
Microfilaments are the thinnest of the cytoskeletal fibers and help maintain the structure of microvilli, which are extensive foldings of the plasma membrane found in cells dedicated to absorption.
They also play a role in muscle cell contraction.