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 lateral root primordia, adventitious root primordia, coleoptiles, shoot apex, leaf primordia, panicles and flowers. Expressed in the apical region (growing zone) of the root hair. Expressed in the growing region of leaves. Expressed in developing seeds. By gibberellin (GA3), submergence and wounding. Belongs to the expansin family. Expansin A subfamily.