The system glycocalyx – membrane bound enzymes – cAMP may be regarded as a regulatory mechanism for the control of epidermal growth. The glycocalyx of the epithelial cell membrane is obviously a receptor and accumulator for agents stimulating adenyl cyclase and other membrane-bound enzymes of energy utilisation; cAMP, on the other hand, serves as an intracellular ‘mediator’ between proliferative stimuli and the DNA of the keratinocytes. Numerous cytological, cytochemical, and enzymatic biochemical studies indicate that this mechanism is profoundly disturbed in psoriasis, particularly at the membrane-bound stage.