Figure 1

The third helix of the human OCT4 protein contains a cell penetrating peptide (orange) enabling the native protein to enter somatic cells. Potentially, native (or truncated) OCT4 can be used to generate integration-free piPSCs in combination with other factors such as small molecules [22] or other cell-penetrating factors and activators of the innate immunity [15] (indicated as ‘X’ in the figure) that can serve as raw materials to produce clinical grade cells for safe cell therapy.