Besides wg, the genome of Drosophila harbors at least three other members of the Wnt gene family, called DWnt-2 (Russell et al., 1992), DWnt-3 (or DWnt-5) (Eisenberg et al., 1992; Russell et al., 1992) and DWnt-4 (Y. Graba and J. Pradel, pers. communication). Although true null mutants to assess the functions of these genes are not available for any of them, their expression patterns suggest important developmental functions. For example, DWnt-2 has a highly dynamic expression pattern, with an early metameric profile and later restriction to the gonads (Russell et al., 1992), while DWnt-3/5 is expressed in the developing CNS (Russell et al., 1992),. DWnt-3/5 encodes a rather unusual protein; compared to other Wnt products it has long inserts and its primary translation product is 113 kD (Eisenberg et al., 1992; Russell et al., 1992). Both genes are initially expressed in thoracic limb anlagen where DWnt-3/5 is regulated by Distalless (Eisenberg et al., 1992), which is in turn itself under the control of wg. One can envisage cascades of inductive factors such as Wnt proteins governing local expression of homeobox genes, which in turn regulate the expression of other secreted patterning molecules.