IntroductionThe Hox gene ceh-13 encodes a transcription factor that is orthologous to the mammalian HOX1 and the Drosophila Labial proteins. In contrast to other C. elegans Hox genes, ceh-13 is required for viability. Animals that lack ceh-13 function arrest as embryos or early larvae with severe, predominantly anterior, body morphology defects. ceh-13 is expressed in well defined cells at various time points throughout development. Not only loss of function but also ectopic expression of ceh-13 has deleterious effects on embryogenesis. Therefore, appropriate spatiotemporal control of ceh-13 is crucial for development. In our lab we concentrate on the characterization of factors that, directly or indirectly, regulate the ceh-13 transcription in the early embryo.