Method for culturing haploid embryonic stem cells

It was discovered that, when Cdc2 was constantly activated in haploid embryonic stem cells, the cell cycle transition from G2 phase to M phase was promoted and thus the haploidy could be maintained. Also, it was discovered that the cultured haploid embryonic stem cells thus obtained showed no variations such as deletion or amplification in the genomic DNA thereof and, furthermore, kept the differentiation/pluripotency and high proliferation potency. According to the present invention, therefore, haploid embryonic stem cells can be cultured while maintaining the haploidy and keeping the differentiation/pluripotency and high proliferation potency without causing any variations in the genomic DNA.