Methods of producing induced pluripotent stem (iPS) cells are provided. For example, a method of producing an iPS cell from a differentiated cell, which includes transforming the differentiated cell with a first vector comprising a nucleic acid sequence comprising a nucleic acid sequence encoding an Oct4, a nucleic acid sequence encoding a Sox2, and a nucleic acid sequence encoding a Klf4. Each of the nucleic acid sequences are separated from each other by a first and second viral 2A sequence. The method described can further comprise culturing the transformed cell under conditions that allow for the production of an iPS cell and isolating the cultured iPS cell.
