The recognition that cellular regulatory circuitry is composed of antagonistic elements has made possible a new approach to the selection of regulatory genes, called the gene-gene interference method. The method was used to identify and isolate genes possibly related in an antagonistic way to protein kinase A. Two such genes were recovered: ART1 encodes a potential regulator of cytokinesis and KAI1 appears to be involved in the Start control. The principles of the gene-gene interference method are discussed, as well as its possible general use for 'walking' within the cellular regulatory networks of eukaryotes.