A NOD signaling adaptor protein that contains two C-terminal leucine-rich domains which recognize bacterial peptidoglycan. It signals via an N-terminal capase recruitment domain that interacts with other card signaling adaptor proteins such as RIP serine-THEONINE KINASES. The protein plays a role in the host defense response by signaling the activation of caspases and the map kinase signaling system. Mutations of the gene encoding the nucleotide oligomerization domain 2 protein have been associated with increased susceptibility to crohn disease.