CARD19 (caspase recruitment domain family member 19), also known as BinCARD-2, is a mitochondrial CARD-containing protein with emerging roles in innate immunity. Originally characterized as a negative regulator of BCL10-mediated NF-κB signaling 1, CARD19 interacts with BCL10 through its CARD domain and suppresses BCL10 phosphorylation in overexpression systems 1. However, recent evidence demonstrates that endogenous CARD19 plays a negligible role in TCR-dependent BCL10-mediated NF-κB activation in primary T cells 2. Instead, CARD19 functions as a positive regulator of antiviral innate immunity by associating with MAVS to facilitate MAVS oligomerization and enhance RIG-I-like receptor signaling, ultimately promoting interferon-β production in response to viral infection 3. Structurally, CARD19's CARD domain is susceptible to redox modification, with all three cysteines capable of oxidation 4, suggesting potential redox-regulatory mechanisms at mitochondria. These findings reveal CARD19 as a multi-functional adapter protein whose primary physiological role centers on potentiating antiviral immune responses rather than inhibiting canonical NF-κB signaling during T cell activation.