Final answer:
Actin-binding proteins and motor proteins determine the organization and behavior of actin filaments inside cells.
Step-by-step explanation:
The organization and behavior of actin filaments inside cells are determined by actin-binding proteins and motor proteins. Actin-binding proteins, such as filamin and α-actinin, help to bundle the actin filaments together and regulate their arrangement. Motor proteins, like myosin, utilize ATP to generate force and interact with actin to cause movement. These proteins play a crucial role in various cellular processes, including muscle contraction, cell shape changes, and cell motility.