GDF6 and hepatocellular carcinoma: The prediction model showed (Figure 1) that seven TGF-β family members (BMP2, BMP6, GDF6, GDF7, GDF10, LEFTY2, and TGF-β1) could be potential independent prognostic factors for HCC, which was validated by Kaplan–Meier survival analysis and ROC analysis (Figure 2), and further by LASSO analysis and PCA analysis (Figure 2).