Novel CARD-12 polypeptides, proteins, and nucleic acid molecules are disclosed. In addition to isolated CARD-12 proteins, the invention further provides CARD-12, fusion proteins, antigenic peptides and anti-CARD-12 antibodies. The invention also provides CARD-12 nucleic acid molecules, recombinant expression vectors containing a nucleic acid molecule of the invention, host cells into which the expression vectors have been introduced and non-human transgenic animals in which a CARD-12 gene has been introduced or disrupted. Diagnostic, screening and therapeutic methods utilizing compositions of the invention are also provided.