title: One problem, two solutions.
authors.forename: Thomas
authors.initials: T
authors.lastname: Boehm
mesh_terms: D000818:Animals; D001402:B-Lymphocytes / Q000166:cytology / Q000276:immunology*; D005075:Biological Evolution; D019070:Cell Lineage / Q000276:immunology; D017578:Immunoglobulin Class Switching / Q000276:immunology; D007798:Lampreys / Q000276:immunology*; D007930:Leucine / Q000378:metabolism; D011946:Receptors, Antigen / Q000276:immunology*; D011971:Receptors, Immunologic / Q000276:immunology; D013601:T-Lymphocytes / Q000166:cytology / Q000276:immunology*
chemical_list: D011946:Receptors, Antigen; D011971:Receptors, Immunologic; D007930:Leucine