Fig. 1.
Reprogramming the differentiated state by viral transduction. The approach initially outlined by Takahashi and Yamananaka (2006) involves the transduction of fibroblast populations (both embryonic and adult) with four pluripotent stem cell factors Klf4, Oct3/4, Sox2, and c-Myc. Transduced cells are then placed under neomycin selection for reactivation of a stem cell-specific promoter (PSC), such as Fbx15, Oct3/4, or Nanog. Resultant colonies were subsequently analyzed functionally, genetically, and epigenetically to assess to what degree they behave like bona fide ES cells.