May cause loosening and extension of plant cell walls by disrupting non-covalent bonding between cellulose microfibrils and matrix glucans. No enzymatic activity has been found. May be required for rapid internodal elongation in deepwater rice during submergence (By similarity). Expressed in mature anthers but not in vegetative or other floral tissues. Causes an allergic reaction in human. Causes grass pollen allergy. Binds to IgE. Belongs to the expansin family. Expansin B subfamily. Sequencing errors.