The growth and/or proliferation of mammalian cells are modulated by modulating the physical interaction between platelets (thrombocytes) and the surface of the cells. Sulfated polysaccharides, preferably glycosaminoglycans, can be used as a medicament for the inhibition of the physical interaction between the cell surface and platelets in the treatment of a medical disorder associated with unwanted cell growth and/or proliferation. The physical interaction between platelets (thrombocytes) and the surface of the cells can be modulated in vitro in order to modulate cell proliferation. Inhibition of the interaction between the cell surface and platelets can inhibit cell growth, and enhancement of the interaction between platelets and the surface of the cell can enhance cell growth.
