CKS1B protein binds to the catalytic subunit of the cyclin dependent kinases and is essential for their biological function. The CKS1B mRNA is found to be expressed in different patterns through the cell cycle in HeLa cells, which reflects a specialized role for the encoded protein. At least two transcript variants have been identified for this gene, and it appears that only one of them encodes a protein. Recombinant human CKS1B protein, fused to His-tag at N-terminus, was expressed in E.coli and purified by using conventional chromatography techniques.