It means that omission of c-Myc and Klf4 from the reprogramming process is important since reactivation of the c-Myc virus in MSCs derived from AD can endogenously express high levels of c-Myc; therefore, we propose that these cells can be reprogrammed into iPSCs merely by OCT-4 expression [37, 39]. The gene discussed is KLF4; the disease is Alzheimer disease.