MAPK1 and hepatocellular carcinoma: Western blot analysis revealed that downregulation or overexpression of circUCK2(2,3) respectively decreased or increased pERK and pAKT levels in HCC cells, without affecting p-p65 (NF-κB) and pSTAT3 (Fig. S11A), These results suggest that circUCK2(2,3)-induced EGFR phosphorylation activates the downstream MAPK-ERK and PI3K-AKT signaling pathways, but does not affect JAK-STAT3 or NF-κB pathways.