CDK1 also known as Cyclin-dependent kinase 1 plays a key role in the control of the eukaryotic cell cycle by modulating the centrosome cycle as well as mitotic onset; promotes G2-M transition, and regulates G1 progress and G1-S transition via association with multiple interphase cyclins. This protein is required in higher cells for entry into S-phase and mitosis. Recombinant human CDK1, fused to His-tag at N-terminus, was expressed in E.coli.