Genes whose expression is subordinate to developmental control genes (q.v.). Downstream genes are switched on or off at various times and in different tissues by transcription factors (q.v.) encoded by upstream regulatory genes. A master controlling gene like eyeless (q.v.) will activate some downstream genes that encode their own transcription factors. The result will be a cascade of proteins that each regulate their own subsets of downstream genes. See gene networking, Hox genes, selector genes.
Subjects: Genetics and Genomics.