RNF43 and cancer: Numerous cancer-linked RNF43 mutations affecting regions outside those encoding essential RNF43 domains, such as the FZD-binding site (found in the PA domain of the N-terminal extracellular domain) and the RING ubiquitination site (found in the RING domain within the cytoplasmic part) possibly point to the existence of an extra mode of RNF43 control.