Endohydrolysis of (1->4)-beta-D-glucosidic linkages in cellulose, lichenin and cereal beta-D-glucans. Expressed in basal region of leaf blade and proximal parts of leaf and floral organ. Early expressed in the development of root hairs within the root differentiation zone. Expressed late in the development of leaf trichomes when the stalks and branches are expanded. Belongs to the glycosyl hydrolase 9 (cellulase E) family.