By activating Rho family GTPases in response to regulatory signals, Rho guanine nucleotide exchange factors (RhoGEFs) often link extracellular signals to intracellular responses. They are, therefore, likely to be important during development. Panizzi and colleagues provide an example of this on p. 921 by revealing essential functions for one vertebrate RhoGEF in ciliated epithelia during development. Human ARHGEF11 activates Rho and promotes the reorganization of the actin cytoskeleton in cultured cells; its Drosophila homologue controls cell shape changes during gastrulation. To study its role in vertebrate development, the researchers used chromosomal deletion and antisense morpholino oligonucleotides to produce zebrafish embryos that lacked functional Arhgef11 (the zebrafish homolog of ARHGEF11). These embryos showed phenotypes often associated with defective ciliated epithelia, including ventrally curved axes, altered left-right patterning, abnormal kidney development and disrupted intracellular distribution of polarised proteins. How Arhgef11 affects the function of ciliated epithelia remains to be elucidated, but these results clearly identify unanticipated roles for this RhoGEF in ciliated epithelia during vertebrate development.