Myofibroblasts gain contractile capability from which proteins?

• A. Keratin and collagen
• B. Actin and myosin
• C. Elastin and fibrillin
• D. Tubulin and dynein

Answer: (B)

Myofibroblast contraction comes from the actin-myosin system inside the cell. Actin filaments provide the track and myosin motor proteins slide along them, powered by ATP, to generate tension in the cytoskeleton. This tension is transmitted to the surrounding matrix through focal adhesions, allowing the cell to pull on and remodel the extracellular matrix during wound contraction.

The other proteins listed don’t drive this intracellular contractile force: keratin and collagen are structural components of cells and the extracellular matrix, elastin and fibrillin confer elasticity to the matrix but aren’t responsible for intracellular contraction, and tubulin with dynein relate to microtubules and transport rather than the actin-based contraction that characterizes myofibroblasts.