Fig. 2.

CENP-U is essential for the viability of mouse ES cells. a Strategy used for generating conditional CENP-U-deficient ES cells. (a) Constructs used for sequential gene targeting. (b) Targeting strategy. Mouse ES cells with CENP-U^flox/− alleles were obtained by sequential gene targeting. When OHT was added to ES cells with CENP-U^flox/− alleles to activate Cre-recombinase (Mer-Cre-Mer), homologous recombination occurred between two loxP sites and ES cells with the CENP-U^Δ/− allele were conditionally obtained. b Genotype analysis of conditional CENP-U-deficient ES cells. After adding OHT to ES cells with CENP-U^flox/− alleles, recombination occurred between two loxP sites. c Immunofluorescence analysis of ES cells with CENP-U^flox/− alleles before or after adding OHT with anti-CENP-U antibody. Scale bar, 10 μm. d Cell growth analysis for ES cells with CENP-U^flox/− alleles in the presence or absence of OHT. e Colony formation efficiency for ES cells with CENP-U^flox/− alleles in the presence or absence of OHT