Loss of XIST signals in 609-iPS cells (XX) and 386-iPSCs (XXX). (a) Representative images of XIST RNA FISH (red)/X chromosome-DNA FISH (green) on 609 fibroblasts, 609-2 iPS cells (passage 5: p5), and 609S-1 iPS cells (p10). 609 fibroblasts have one XIST signal. Most 609-2 iPS cells retain XIST expression. In contrast, 609S-1 iPS cells, which were generated with Sendai viral vectors, had totally lost XIST expression. Quantitative data are also shown in Table 2. (b) Representative images of XIST RNA FISH (red)/X chromosome-DNA FISH (green) on 386 fibroblasts, and 386-S19 iPS cells. 386 fibroblasts have three X and two XIST signals. 386-S19 iPS cells, which were induced using Sendai viral vectors retained one XIST expression. Trimethyl-histone H3 (Lys27) (H3K27me3) signals (red) in 386-S19 iPS cells are shown. Most cells have just one H3K27me3 signal/cell. (c) XIST signals per cell in 386 fibroblasts and four 386 iPS cells. 386 fibroblasts have three X chromosomes and two XIST signals. In four 386 iPS clones, which were induced with Sendai viral vectors, most cells have one XIST signals.