Time-dependent changes in qPCR induced by exogenous reprogramming genes in three-factor or four-factor iPSCs. mRNA encoding exogenous OCT3/4 (A), SOX2 (B), KLF4 (C), and c-MYC (D) in human ES cells (ESCs), TkDN4-M (three-factor iPSCs), TkDA3-2, TkDA3-4, and TkDA3-5 (four-factor iPSCs) on day 0 or their derivatives (on days 6, 10, 15, 22, and 26 after initiation of MK-lineage culture) were examined by qPCR as described in the Materials and methods section. TkDA3-4–derived mature MKs (day 26) was assigned a value of 1.0 (n = 4, means ± SEM from two independent experiments).