Homeobox genes in normal and malignant cells

Homeobox genes are transcription factors primarily involved in embryonic de velopment. Several homeobox gene families have so far been identified: Hox, EMX, PAX, MSX as well as many isolated divergent homeobox genes. Among the se, Hox genes are most intriguing for having a regulatory network structure organization. Recent indications suggest the involvement of homeobox genes in (i) crucial adult eukariotic cell functions and (ii) human diseases, sp anning from diabetes to cancer. In this review we will discuss the mechanis ms through which homeobox genes act, and will propose a model for the funct ion of the Hox gene network as decoding system for achieving specific genet ic programs. New technologies for whole-genome RNA expression will be cruci al to evaluate the clinical relevance of homeobox genes in structural and m etabolic diseases. J. Cell. Physiol. 188: 161-169, 2001. (C) 2001 Wiley-Lis s, Inc.