We also tried to generate human iPSCs (hiPSCs) by infection of 3×104 human neonatal dermal fibroblasts with Ai-LV encoding human version of three reprogramming factors (Oct4, Klf4 and Sox2) with or without human c-MYC encoding lentiviral vector; however we could only generate two hiPSC colonies when the c-Myc vector was infected. This evidence concerns the gene KLF4 and infection.