MEF2D and hepatocellular carcinoma: Two lines of evidence suggest that MEF2D itself may undergo feedback regulation by the pro‐metastatic niche signals: (i) the MEF2D‐regulated gene signature was increased in intrahepatic metastases compared with primary HCC tissues (Figure S1C, Supporting Information); and (ii) the protein abundance of MEF2D was elevated upon interacting with niche components in a time‐ and dose‐dependent manner (Figures 2D and 4A; Figures S3D and S8A,B, Supporting Information).