GDF2 and hepatocellular carcinoma: Consistent with this hypothesis, xenografts derived from HBV‐infected HCC cells showed extensive leakage of intravenously administered FITC‐dextran compared with those derived from HBV‐uninfected HCC cells; conversely, xenografts derived from BMP9‐overexpressing HBV‐infected HCC cells exhibited an absence of leakage (Figure 4C).