SFRP2 and cholangiocarcinoma: It has been reported that global alterations of DNA methylation in CCA target the Wnt signaling pathway, and that promoter silencing of Wnt signaling-related genes such as SOX17, WNT3A, DKK2, SFRP1, SFRP2, and SFRP4 is reversed upon treatment of CCA cell lines with 5-aza-2’ deoxycytidine [39].