Axin: a master scaffold for multiple signaling pathways.

Axin was originally identified from the characterization of the Fused locus, the disruption of which leads to duplication of axis and embryonic lethality. It is a multidomain protein that interacts with multiple proteins and functions as a negative regulator of Wnt signaling by downregulating the beta-catenin levels. Recently, it was demonstrated that Axin also plays an important role in a JNK signaling pathway. Axin utilizes discriminatory domains for its distinct roles in the Wnt pathway and in the Axin/JNK pathway. Here we review the data that show how Axin regulates multiple signaling pathways by serving as a scaffold protein, controlling diverse cellular functions in proliferation, fate determination, and suppression of tumorigenesis. Copyright 2004 S. Karger AG, Basel