N4BP1 (NEDD4 binding protein 1) is a potent suppressor of cytokine production that acts as a key negative regulator of innate immune signaling and inflammation 1. The protein functions through multiple mechanisms: it degrades target mRNAs via its endoribonuclease activity by recognizing C-rich motifs in coding sequences rather than 3'-UTRs 2, and it inhibits NF-κB signaling pathway activation 3. N4BP1 selectively suppresses TRIF-independent Toll-like receptor responses (TLR1/2, TLR7, TLR9) but is cleaved and inactivated by caspase-8 downstream of TLR3/TLR4 signaling, allowing inflammatory cytokine production in response to major threats 1. The protein also acts as an antiviral restriction factor, working with TRIM25 and KHNYN to degrade viral RNAs, including HIV-1 mRNAs 4. N4BP1 is a nucleocytoplasmic shuttling protein that forms aggregates containing neddylated proteins like cullin-1 and cullin-2, providing cellular protection under heat shock conditions 5. Clinically, N4BP1 plays protective roles in skin injury and burn healing by regulating keratinocyte development and targeting MMP9 6. Viral proteases can cleave N4BP1 to evade host immune responses, highlighting its importance in antiviral defense 7.