NOTCH1 and cholangiocarcinoma: In NICD plasmid transfected CCA cells, the p-Erk1/2 and p-Akt expression were upregulated in comparison to control cells, which indicated that NICD directly affects the manifestation of downstream target genes, even though exogenous NICD resulted in diminished expression of Notch1, which acts as a negative feedback inhibitor [106].