RNF43 and colorectal cancer: The tumor suppressor ubiquitin ligase RNF43 (RING finger protein 43), one of the protein components of the pathway with a high mutation prevalence in CDX2-suppressed colorectal cancers, is a down-regulator of the Frizzled receptors of the pathway, through ubiquitination leading to the proteasome degradation of the receptors and decreased pathway activity [34].