CARD9 binds RIP2 and NOD2. In addition overexpression of CARD9 strongly activates the kinases p38 and Jnk while CARD9-deficient mouse macrophages have defects in activation of p38 and Jnk but not NF-kappaB signaling, suggesting that CARD9 is involved in an NF-kappaB-independent signaling pathway (Hsu et al. 2007), but the mechanism is unclear. CARD9 is the key transducer of signals from dectin-1, the major mammalian pattern recognition receptor for the fungal component zymosan (Gross et al. 2006).