Hb levels and GFP⁺ RBC chimerism in peripheral blood of hyper- and hypotransfused CA mice. Humanized CA mice were transfused weekly with packed donor RBCs from GFP⁺ transgenic mice. Two days after transfusion, mice were bled for determination of Hb level by spectrophotometry (A) and percentage of donor GFP⁺ RBCs by flow cytometry (B). Values represent mean (± SEM), n = 5 in each group.