Fig. 12. A network of interactions in the regulation of derrière. Solid black arrows indicate direct actions of VegT and dotted black arrows indicate effects of VegT that may be indirect. Solid grey arrows indicate probable direct interactions of derrière and nodal-related gene products on the derrière promoter, which occur after the initial effects of VegT. Dotted grey arrows indicate the effects of gene X on the derrière promoter and of the nodal-related proteins on the VegT 5' regulatory region, causing the activation of Antipodean. Gene X is yet to be identified, but may represent a member of the FGF family. See text for details.