<n0:ComplexDefinition xmlns:n0="http://ncicb.nci.nih.gov/xml/owl/EVS/ComplexProperties.xsd#"><n0:def-definition>Proteins that are related to bcl-2 are characterized by the presence of one or more highly conserved stretches of homology with bcl-2, designated BH1, BH2, BH3, BH4. These domains control the ability of these proteins to homo- and heterodimerize with other proteins. Competitive dimerization between family members is thought to regulate their function as regulators of apoptosis.</n0:def-definition><n0:def-source>NCI</n0:def-source></n0:ComplexDefinition>