The structure of the MAS1 product indicates that it belongs to the class of receptors that are coupled to GTP-binding proteins and share a conserved structural motif, which is described as a '7-transmembrane segment' following the prediction that these hydrophobic segments form membrane-spanning alpha-helices. The MAS1 protein may be a receptor that, when activated, modulates a critical component in a growth-regulating pathway to bring about oncogenic effects.