YAP1 and cholangiocarcinoma: When the Hippo-signaling pathway is inactivated, dephosphorylated YAP1 is translocated to the nucleus where it interacts with transcription factors, eventually leading to the proliferation of cells to various organ systems.[17]–[20] One previous study using transgenic mice with liver-specific YAP1 overexpression revealed significant increases in liver size and number of primary liver tumors morphologically resembling cHC-CC in humans.[21]