COVER PHOTOGRAPH: Signaling by the Wingless morphogen (a member of the Wnt family of secreted glycoproteins) is required for the proper development of appendages in Drosophila. Overexpression of Axin, a negative regulator of Wnt signaling, leads to severe defects in Drosophila wing growth and patterning (the affected wing is shown in a green pseudocolor, compared to a wild-type wing in pink). The inhibitory activity of Axin can be suppressed by co-expression of the GTP-binding protein Gαo, leading to a partial rescue in wing development (yellow). Gαo physically binds the RGS domain of Axin and recruits Axin it to the plasma membrane, antagonizing the Axin-based destruction complex. From Egger-Adam and Katanaev, Developmental Dynamics 239:168–183, 2010. © 2009 Wiley-Liss, Inc.