KLF4 and Parkinson disease: We have established iPS cells from cutaneous fibroblasts obtained from patients with the PARK2 form of familial PD (Patient A: female with an exon 2–4 deletion mutation; Patient B: male with an exon 6–7 deletion mutation) by performing retroviral gene transduction (Oct4, Sox2, Klf4, and c-Myc) [15, 21].