Phosphorylates inhibitors of NF-kappa-B thus leading to the dissociation of the inhibitor/NF-kappa-B complex and ultimately the degradation of the inhibitor. Phosphorylates 'Ser-10' of histone H3 at NF-kappa-B-regulated promoters during inflammatory responses triggered by cytokines. ATP + L-seryl-[I-kappa-B protein] = ADP + H(+) + O-phospho-L-seryl-[I-kappa-B protein] Activated when phosphorylated and inactivated when dephosphorylated. Directly interacts with ikbkg/nemo. Shuttles between the cytoplasm and the nucleus. Abundantly expressed from the blastula period through early gastrulation. During early somitogenesis, transcripts are dorsally localized at the level of the segmental plate and the presumptive notochord. At the 18-somite stage, expression becomes largely detectable throughout the somitic tissue At late embryonic stages, expression is particularly evident in the tectum, cerebellum, hindbrain region, and eyes. After hatching, transcripts can also be detected in the myotomes and pectoral fins. Belongs to the protein kinase superfamily. Ser/Thr protein kinase family. I-kappa-B kinase subfamily.