Acts as a ventralizing factor during embryogenesis. Inhibits axin-mediated JNK activation by binding axin and disrupting axin homodimerization. This in turn antagonizes a Wnt/beta-catenin-independent dorsalization pathway activated by AXIN/JNK-signaling. Predicted to enable phosphatidylinositol binding activity. Acts upstream of or within negative regulation of JUN kinase activity. Predicted to be located in cytoplasm. Predicted to be active in membrane.