Disclosed herein is the finding that Zscan4 is an early embryonic factor that facilitates cellular reprogramming. In particular, Zscan4 can replace the oncogenic reprogramming factor c-Myc to produce induced pluripotent stem cells when co-expressed with Klf4, Oct4 and Sox2. In addition, several Zscan4-dependent genes were identified that promote iPSC formation when co-expressed with known reprogramming factors. Thus, the present disclosure provides an ex vivo method of producing an iPS cell by reprogramming of a somatic cell. The method includes contacting the somatic cell with a Zscan4, or a Zscan4-dependent gene, and at least one reprogramming factor. Also provided are iPS cells produced by the disclosed method and non-human animals generated from such iPS cells.