Vertebrate coding sequences (GenBank accession nos) retrieved from the database define six groups of closely related Iroquois genes. Sequence assemblies of partial cDNAs (or of exon-containing genomic DNA) representing the same gene are boxed together. Database entries and names of published cDNAs are shown in boldface, all other entries are derived from database searches described in this article. Sequence entries for homologous genes present in Drosophila andCaenorhabditis elegans are: caupolican (X95178),araucan (X95179), mirror (U95021), andC36F7.1 (Z81045).