Definition for Expansin
From Biology Forums Dictionary
1) A protein that occurs in the plant cell wall and fosters cell enlargement.
2) Expansin refers to a family of closely related nonenzymatic proteins found in the plant cell wall, with important roles in plant cell growth, fruit softening, abscission, emergence of root hairs, pollen tube invasion of the stigma and style, meristem function, and other developmental processes where cell wall loosening occurs.