Question

What is the cytoskeleton made of?

Answer 1

Protein

Explanation:

Cytoskeleton is composed of a contractile protein called actin which is the most abundant cellular protein.

Answer 2

There are three primary "fibers" in cytoskeleton:

1. Microfilaments
2. Microtubules
3. Intermediate filaments

I've tabulated these below,

Clearly, the functions are simplified. Your question is regarding the protein monomers, though.