NALP proteins include the apoptosis regulator APAF1 (apoptotic protease activating factor 1) and mammalian NOD-LRR proteins and are thought to be involved in inflammation and reproduction. NALP6, also known as PYPAF5, is highly expressed in granulocytes and T cells and co-localizes with the PYRIN-CARD protein ASC. Co-expression of NALP6 with ASC results in a synergistic activation of NF-kappaB and activated caspase-1-dependent cytokine processing, suggesting that NALP6 functions in immune cells to coordinate the transduction of pro-inflammatory signals.