MUC1 and cholangiocarcinoma: The anti-MUC1-CAR4 T cells increased granzyme B production in an antigen-specific manner after exposure to MUC1-expressing CCA cells, KKU-100 and KKU-213A (26.9 ± 0.61% and 32.3 ± 2.34%, respectively), compared to those of UTD T cells (10.77 ± 0.65% and 11.8 ± 0.79%, respectively).