Furthermore, catalpol, an R. glutinosa extract, can synergistically increase the antitumor effects of regorafenib in HepG2 and HUH-7 HCC cell lines by inhibiting VEGF/VEGFR2, PI3K/Akt/mTOR, and NF-κB signaling pathways [72]. This evidence concerns the gene KDR and hepatocellular carcinoma.