SFRP1 and cholangiocarcinoma: As stated before, SFRP1 has been shown to be a candidate tumor suppressor gene.19 On the basis of our observation that Dicer is functionally involved in promoter methylation and transcriptional silencing of SFRP1 (Figures 3d and 4a), we next investigated a potential role of Dicer in the pathogenesis of CCA.