Involved in the regulation of innate immune response (By similarity). Acts as negative regulator of Toll-like receptor, interferon-regulatory factor (IRF) and canonical NF-kappa-B signaling pathways (By similarity). Contributes to the regulation of transcriptional activation of NF-kappa-B target genes in response to endogenous pro-inflammatory stimuli (By similarity). Interacts (via N-terminal domain) with NFKBIL1; the interaction occurs in a pro-inflammatory-independent manner (By similarity). Does not interact with RELA NF-kappa-B subunit (By similarity). Identified in the spliceosome C complex (By similarity). Nuclear localization with a speckled expression pattern in some cells. Colocalizes with NFKBIL1 in the nucleus (By similarity). Expressed in cortex, hippocampus, cerebellum, heart, lung, kidney, liver, spleen and thymus. Belongs to the CACTIN family.