The present invention provides a method of inhibiting an activity of a cell regulatory factor comprising contacting the cell regulatory factor with a purified polypeptide, wherein the polypeptide comprises the cell regulatory factor binding domain of a protein and wherein the protein is characterized by a leucine-rich repeat of about 24 amino acids. In a specific embodiment, the present invention relates to the ability of decorin, a 40,000 dalton protein that usually carries a glycosaminoglycan chain, to bind TGF-.beta.. The invention also provides a novel cell regulatory factor designated MRF. Also provided are methods of identifying, detecting and purifying cell regulatory factors and proteins which bind and affect the activity of cell regulatory factors. The present invention further relates to methods for the prevention or reduction of scarring by administering decorin or a functional equivalent of decorin to a wound. The methods are particularly useful for dermal wounds resulting from burns, injuries or surgery. In addition, the present invention includes pharmaceutical compositions containing decorin or its functional equivalent and a pharmaceutically acceptable carrier useful in such methods. Finally, methods for preventing or inhibiting pathological conditions by administering decorin are also provided.