A method for the generation of human induced pluripotent stem (iPS) cells was established. This method employs adenovirus carrying the ecotropic retrovirus receptor mCAT1 and Moloney murine leukemia virus (MMLV)-based retroviral vectors carrying the four transcription factors POU5F1 (OCT3/4), KLF4, SOX2, and MYC (c-Myc) (Masaki H & Ishikawa T Stem Cell Res 1:105-15, 2007). The differentiation of human iPS cells into hepatic cells was performed by a stepwise protocol (Song Z et al. Cell Res 19:1233-42, 2009). These cells have potential as patient-specific in vitro models for studying disease etiology and could be used in drug discovery programs tailored to deal with genetic variations in drug efficacy and toxicity.