Three groups of bone marrow chimeric animals were generated: (1) Gch1fl/flTie2CreApoE–/– were given bone marrow from Gch1fl/flApoE–/– to assess the impact of loss of Gch1 from endothelial cells on atherosclerosis progression; (2) Gch1fl/flApoE–/– received Gch1fl/flTie2CreApoE–/– bone marrow to assess the role of leucocyte Gch1; or (3) Gch1fl/flApoE–/– received Gch1fl/flApoE–/– bone marrow, as a control group. The gene discussed is GCH1; the disease is atherosclerosis.