title: New look at an old costimulator.
authors.forename: Peter S
authors.initials: PS
authors.lastname: Linsley
mesh_terms: D000938:Antigen-Presenting Cells / Q000276:immunology; D018106:CD28 Antigens / Q000737:chemistry / Q000276:immunology / Q000502:physiology*; D006801:Humans
chemical_list: D018106:CD28 Antigens