Expression of human γ-globin protein in erythrocytes of ASpEx1IVS1/^Aγ-transgenic mice. Fluorescence intensity from a FITC-conjugated monoclonal antibody against human γ-globin was correlated with the number of erythrocytes counted in 6 representative transgenic lines chosen for high ^Aγ-globin mRNA expression. In each panel, the thick line represents a transgenic mouse and the thin line represents a nontransgenic, littermate control. The single peaks observed represent uniform expression of human γ-globin in these cells, whereas a bimodal peak represents nonuniform or variegated expression.²³  Representative transgenic lines are shown, with the letters corresponding to Table S3.