Expression of the erythroid lineage in M1 clonal lines transfected with the GATA-1 expression vector. Cells were incubated with biotinylated TER-119 and FITC-conjugated streptavidin. (A) M1 clone transfected with the control vector (M1/pMG2), (B) M1GATA-Y1 clone, (C) M1GATA-Y22 clone, (D) M1GATA-Y25 clone. (^_____), unstained cells; (----), stained cells.