The present invention provides NB-ARC and CARD-containing proteins (NACs), nucleic acid molecules encoding NACs and antibodies specific for at least one NAC. The invention further provides chimeric NAC proteins. The invention also provides screening assays for identifying an agent that can effectively alter the association of a NAC with a NAC-associated protein. The invention further provides methods of modulating apoptosis in a cell by introducing into the cell a nucleic acid molecule encoding a NAC or an antisense nucleotide sequence. The invention also provides a method of using a reagent that can specifically bind to a NAC to diagnose a pathology that is characterized by an increased or decreased level of apoptosis in a cell.