The hox/hom previous termhomeobox genesnext term code for DNA-binding proteins that confer positional information during animal development; these previous termgenesnext term have been found in a wide range of triploblasts and in cnidarians. We report here the identification of a hox/hom previous termgenenext term and two other previous termhomeobox genesnext term in the genomes of previous termsponges.next term This finding extends the detection of hox/hom previous termgenesnext term to the lowest metazoan phylum and suggests a monophyletic origin of the kingdom Animalia. Because, in culture, previous termspongenext term cells quickly reaggregate, differentiate and construct tissue after disaggregation, they can provide a useful model system for characterization of the basic roles of previous termhomeobox genesnext term in the control of cellular differentiation