To explain why tHSCs had a stronger effect on HCC progression, we quantitatively determined some of these factors in tHSC-CM, qHSC-CM and aHSC-CM, and found that tHSCs produced higher levels of TGF-β, HGF, PDGF and VEGF than did qHSC and aHSC cells (Figure S5), further suggesting tHSCs as key regulators of the paracrine signaling between stromal and HCC cells. This evidence concerns the gene HGF and hepatocellular carcinoma.