Subsequently, we constructed in situ CCA models in C57BL/6 mice as well as TET1 conditional knockout mice (tet1‐CKO) by hydrodynamic tail vein injection and the Sleeping Beauty transposon[20] (Figure 1F) to examine the differences between cancerous and normal tissues in terms of TET1 expression, as well as the effects of TET1 on CCA progression and survival in vivo. Here, TET1 is linked to cholangiocarcinoma.