MYC is a regulator gene that codes for a transcription factor is believed to regulate expression of 15% of all genes. L-MYC is an isotype of the MYC family. It has been shown that L-Myc can take c-Myc's place and generate safer iPS cells at higher efficiencies. L-MYC lentivirus (CMV, Puro) expresses human L-Myc under the control of the CMV promoter with puromycin as a selection marker.