APOE and hepatocellular carcinoma: Adenovirus, encoding the HSV-TK gene driven by hTERT-targeting trans-splicing ribozyme under the control of liver-specific phosphoenolpyruvate kinase (PEPCK) promoter with an ApoE enhancer placed in the distal region of the HSV-TK expression cassette, showed significant anti-tumor efficacy in a multifocal HCC model with splenic subcapsular inoculation of Hep3B cells in nude mice without damaging normal hepatocytes.