MAPK1 and intrahepatic cholangiocarcinoma: Moreover, circPCNXL2 is significantly upregulated in the tissues of patients with intrahepatic cholangiocarcinoma (ICC) and promotes the interaction of STEP and MEK1/2 by directly binding to the protein STEP, thereby upregulating the ERK/MAPK axis to accelerate tumor progression and reducing the antitumor effect of trametinib.98