AbstractA cell growth factor protein (insulin) and/or a cell‐adhesion protein (fibronectin) were immobilized on surface‐hydrolyzed poly(methyl methacrylate) membranes. The growth of mouse fibroblast cells STO was accelerated by the immobilized insulin. This acceleration was enhanced by introduction of spacer arms. Coimmobilization of insulin and fibronectin was very effective for the acceleration of cell growth. © 1993 John Wiley & Sons, Inc.