Casein kinase II subunit alpha 3 is a protein in humans that is encoded by CSNK2A3 gene. Probable catalytic subunit of a constitutively active serine/threonine-protein kinase complex that phosphorylates a large number of substrates containing acidic residues C-terminal to the phosphorylated serine or threonine. Amplification-dependent oncogene; promotes cell proliferation and tumorigenesis by down-regulating expression of the tumor suppressor protein, PML. May play a role in the pathogenesis of the lung cancer development and progression.