Abstract: The disclosure generally provides proteins that bind two epitopes (e.g., a first and a second epitope) and that are bivalent for binding to each of the first and second epitopes. The disclosure also provides for specific binding proteins, including antibodies, which bind to a target protein. The disclosure also provides compositions comprising such proteins, nucleic acid molecules encoding such proteins and methods of making such proteins. The disclosure provides methods of inducing an immune response in a subject as well as methods for treating or preventing cancer in a subject by administering the proteins, nucleic acid molecules and/or compositions to the subject.