TBX1 and cholangiocarcinoma: Although CAFs are one of the most abundant stromal cell types in the CCA TME [53], potential sources of CAFs in CCA remains unclear, and CAFs may potentially derive from quiescent hepatic stellate cells (HSCs), portal fibroblasts, bone marrow-derived fibroblasts, as well as cholangiocytes-derived fibroblasts via epithelial mesenchymal transition.