It is now generally recognized that protein kinase signaling is involved in virtually every aspect of cell function, including growth and proliferation. The field of protein phosphorylation, including the enzymes involved in this post-translational modification, continues to advance at a fascinating pace. Since the first international meeting on this topic, held in Heidelberg in 1994, several new avenues of CK2 research have emerged despite persistent deficiencies in our understanding of the regulation of its activity. Among the significant new directions are studies related to the structure of the enzyme, especially its crystal structure, as well as an interesting aspect of CK2 function that involves its subunits