NF-κB is an important transcription factor for immune cell development and function and is regulated by IκB proteins. IκBNS is an unusual IκB protein and functionally poorly characterized. During the 2nd funding period, A 23 established that IκBNS-/- mice are resistant towards high-dose Listeria infection, hinting towards alterations in innate immunity. Indeed, we found extraordinarily high expression of IκBNS in macrophages/monocytes, neutrophils and NK cells using reporter mice. In the next funding period, we will decipher molecular and cellular functions of IκBNS in these cells using newly established conditional knockout mice that are currently being characterized. This includes IκBNS-dependent leucocyte migration during Listeria infection and functional characterization of target genes and microRNAs.