Casein kinase II (CKII) exhibits broad phosphorylation reaction on various important regulatory proteins such as survival factors in eukaryotic cells. Since the relationship of CKII over-expression to carcinogenesis and cancer metastasis has been reported, CKII is considered to be one of the drug target proteins. Here, we aimed to obtain the structural information with location of hydration water molecules, and to elucidate the catalytic reaction of CKII for development of effective inhibitors
