MUC1 and cholangiocarcinoma: Research has found that CAR-T cells targeting integrin αvβ6 and mucin 1, expressed on bile duct cancer cells, can be utilized in adoptive T cell therapies for bile duct cancer (106–109).However, MUC1 overexpression is also linked with the upregulation of PD-L1, an immune checkpoint protein that inhibits the antitumor function of T cells, which may lead to reduced efficacy of MUC1-targeting CART cell therapy for cholangiocarcinoma.