TET1 and cholangiocarcinoma: For example, a comparative study conducted in 2017 revealed that TET1 expression in CCA is inhibited by miR‐191, which maintains the CpG‐rich methylated region of the transcription start site of the p53 gene methylated, resulting in reduced p53 expression and diminished anticancer activity of p53.[37a] A 2021 study investigated the effects of α‐KG and dimethyl‐α‐KG (DM‐α‐KG) on CCA cells.