DNMT1 and cholangiocarcinoma: Studies have shown that DNMT1 is abnormally expressed in many tumor types [64,65], and their regulation by miR-148/152 family members has been reported in a number of human diseases including systemic lupus erythematosus [55], cholangiocarcinoma [36], hepatocellular carcinoma [32], acute lymphoblastic leukemia [46] and endometrial cancer [62].