Abstract: A method of cloning mammalian genes encoding proteins which can function in microorganisms, particularly yeast, and can modify, complement, or suppress a genetic defect associated with an identifiable phenotypic alteration or characteristic in the micro-organism. It further relates to mammalian genes cloned by the present method, as well as to products encoded by such genes and antibodies which can bind the encoded proteins. More specifically, the present invention relates to a method of cloning mammalian genes which encode products which modify, complement or suppress a genetic defect in a biochemical pathway in which cAMP participates or in a biochemical pathway which is controlled, directly or indirectly, by a RAS protein, to products (RNA, proteins) enocded by the mammalian genes cloned in this manner and to antibodies which can bind the encoded proteins.