Soybean (Glycine max) suspension-cultured cells were incubated with 600 micromolar uridine diphosphate [14C]glucose, and the incorporation into alkali-insoluble material was studied. When the cells were kept in suspension by shaking on a linear shaker, the incorporation was very low. The incorporation was stimulated 30-fold when the cells were continually resuspended by stirring with a narrow glass rod. The stirring procedure was shown to damage some of the cells, and the incorporation appeared to be a wound response. The alkali-insoluble material formed was a β-(1→3)-glucan, and it was synthesized from uridine diphosphate glucose which did not penetrate through the plasma membrane of intact cells. The synthetase activity was probably induced by the stirring procedure. No evidence for cellulose synthesis from extracellular uridine diphosphate glucose was obtained.