N-myc (also MYCN) proto-oncogene was very highly enriched in a number of stem cells, including hematopoietic as well as both human and murine embryonic stem cells. N-Myc has been used to generate iPS cells. N-MYC lentivirus (TET-inducible, Puro) expresses human N-Myc under the control of the Tet responsive promoter with puromycin as a selection marker.