The IκB kinase (IKK) complex plays a crucial role in the activation of the transcription factor NF-κB by phosphorylating an inhibitory molecule IκBα. Recently, we showed that IKK2 (also called IKKβ), a catalytic subunit of the IKK complex, induces immunoglobulin E-mediated degranulation in mast cells by phosphorylating SNAP-23, the target-membrane soluble N-ethylmaleimide-sensitive fusion factor attachment protein receptor (SNARE).