Fig. 3: Radiosensitivity of iPSC generation.

a Nanog-GFP MEFs infected with Yamanaka 4 factors (OSKM) were exposed to 3 Gy X-ray irradiation on each day post-infection up to day 6 (culture condition [1]. See Supplementary Fig. 6). GFP+ (Nanog+) colonies were counted on day 14. Error bars denote the standard deviation (SD) of the mean (n = 3 independent culture dishes). *P < 0.05. Results are representative of three independent experiments with three replicates per group. Control, without ionizing radiation (IR). For statistical analysis, two-sided Mann–Whitney U test was performed. b Cell cycle analysis using EdU and propidium iodide (PI) in a Dox-inducible system. The cells used were MEFs derived from a chimeric mouse generated with a GFP-positive iPSC line containing the Dox-inducible transgene constructs encoding the four reprogramming factors (see Supplementary Fig. 9a). Control cells were doxycycline-untreated GFP-negative normal primary fibroblasts prepared from the chimeric embryos. To control for possible effects of culture medium replacement, this analysis was conducted with no replacement of the growth medium throughout the iPSC generation process from Dox induction (culture condition [4]). Notably, similar results were also obtained using original culture conditions [3]. c Western blot analysis of cell cycle-related proteins on days 1–6 using whole cell lysates prepared at 6, 12, and 24 h after 3 Gy irradiation (MEF, 4F retroviral system, culture condition [1]). Two different controls were used as follows: empty vector infection alone (Vec only) and c-Myc infection alone (Myc only). Cell extracts were prepared each day at 6, 12, and 24 h after 3 Gy irradiation. The signals normalized to the GAPDH signal are also shown (Supplementary Fig. 12). In addition, because the sample set for each day was analyzed with different western blots, an internal control was loaded to normalize the exposure time. Source data are provided as a Source Data file.