We also detected the apoptosis of CCA cells by flow cytometry, and found that the percentage of cell apoptosis increased after USP1 was knocked out in HuCC-T1, and decreased after overexpression of USP1 in RBE, both effects can be reversed through the overexpression or knockdown of PARP1, respectively (Sup. This evidence concerns the gene USP1 and cholangiocarcinoma.