KLF4 and infection: Human iPSC lines and AF-IPS and FF-IPS cell lines were independently established in our laboratory using infection with the STEMCCA lentivirus (containing doxycycline-inducible human OCT4, SOX2, KLF4 and c-MYC) or episomal vectors containing 6 factors (Oct4, Sox2, L-Myc, Lin28, Nanog and Klf4) from 2 fully differentiated parental cell types (AF and FF cells).