CREB1 and hepatocellular carcinoma: Studies have shown that PGE2 can significantly up-regulate C-myc expression at both mRNA and protein levels, while knocking down C-myc can block PGE2-induced HCC cell growth and human hepatoma cell line Huh7 invasive ability; this process may be achieved through the EP4/GS/AC/cAMP/PKA/CREB signaling pathway (Xia et al., 2014).