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). In addition to IKK2, a recent 
study has shown that ELKS, a regulatory subunit of the IKK complex, also induces 
the degranulation of rat basophilic leukemia cells. These findings indicate that 
the two subunits of the IKK complex, IKK2 and ELKS, function not only in 
NF-κB-dependent transcriptional activation but also in NF-κB-independent 
pathways. This review focuses on the functions of IKK2 and ELKS in mast cell 
degranulation.