POU5F1 and amyotrophic lateral sclerosis: In this study, hiPSC-derived motor neurons were obtained from sporadic ALS patients by reprogramming motor nerve-derived fibroblasts using a STEMCCA Cre-Excisable Constitutive Polycistronic Lentivirus System containing the four transcription factors OCT4, SOX2, KLF4, and CMYC (Somers et al., 2010).