To determine the role of BUB1B in the proliferation of CCA cells, we used virus transfection to knockdown BUB1B in HCCC9810 and RBE cells and plasmid to overexpress BUB1B in QBC939 cells (with relatively low BUB1B level), respectively (Supplementary Fig. 3A–C). Here, BUB1B is linked to cholangiocarcinoma.