Chromosome, a substance to pass our genome from mother to daughter cells, is highly organized structure that is changed dynamically under the regulation of cell cycle. To divide the genome successfully into two daughters, chromosomes, in the first place, must establish sister-chromatid cohesion during DNA replication, otherwise they are randomly separated and an equal distribution of the genome would not be possible. Next, in mitosis, chromosomes must be packed into a micrometer-sized spindle apparatus, which captures chromosomes in a bipolar fashion. How does chromosome achieve those events towards successful segregation? The aim of our group is to understand molecular mechanisms that organize chromosome structure toward proper chromosome segregation and chromosome functions. Specifically, we are focusing on the questions: 1) how cohesin organizes chromosome structure during cell cycle, and 2) how genome is packed into mitotic chromosomes to achieve successful chromosome segregation.