Semiquantitative RT-PCR analysis of the expression of β₂-microglobulin (as control), of β-globin, and of the total (GATA-1), proximal (GATA-1p), and distal (GATA-1d) GATA-1 transcripts in the spleens of untreated or day-1 PHZ-treated wild-type and GATA-1^low mice.

Each product was analyzed for increasing numbers of cycles as indicated by a triangle on the top of the panels. In particular, the products were analyzed after 18, 21, 24, and 27 cycles for β₂-microglobulin; 15, 18, 21, and 24 cycles for β-globin; 20, 24, 26, and 30 cycles for the total GATA-1 transcripts; and 20, 25, 30, and 35 cycles for the GATA-1p and GATA-1d transcripts. The failure of the amplification of transcripts originating from the distal (or testis) GATA-1 promoter28 with the use of cDNA prepared from the GATA-1^low spleens represents an indirect control of the genotype of the mutant mice analyzed in this study. Similar results were obtained in 3 additional experiments.