Protein kinase CK2 is a ubiquitous Ser/Thr/Tyr kinase essential for cell viability in eukaryotes. It comprises alpha catalytic and beta regulatory subunits, which combine to form the classical tetrameric structure, alpha2beta2. Although CK2 is a component of the network that controls the eukaryotic cell cycle, very little is known about the expression patterns of genes encoding its constituent subunits, especially in plants. A study of the complexity of CK2alpha- and CK2beta-encoding genes in BY-2 cells was undertaken in this work, and cloning of the different members of the gene families was performed. The expression of the individual members of each family in relation to cell proliferation was measured by real time RT-PCR. The data obtained provide an accurate understanding of the transcriptional regulation of CK2 in relation to the cell cycle and cell proliferation.