May be involved in the sloughing (cell-cell separation) of the root cap cells from root tip. Endohydrolysis of (1->4)-beta-D-glucosidic linkages in cellulose, lichenin and cereal beta-D-glucans. Specifically expressed in root cap cells. Down-regulated by auxin (IAA) and abscisic acid (ABA). The sloughing of root-cap cells from the root tip is a process of cell-cell separation that entails cell wall break down. It is important in plant development because it assists the growing root in penetrating the soil. Belongs to the glycosyl hydrolase 9 (cellulase E) family.