TPO treatment increased expression of TGFB1 mRNA in cells from femur and spleen of wild-type mice but not in those from their GATA-1^low littermates. Semiquantitative RT-PCR analysis for the expression of TGFB1, PDGF, and β₂-microglobulin (β₂-mg, as control), in femur and spleen from untreated or TPO-treated (7 and 14 days after being treated with 100 μg TPO/kg per day for 5 days) wild-type and GATA-1^low littermates. Each product was amplified for increasing number of cycles,^25,30,35  as indicated by the triangle on the top of the panels. Similar results were obtained in 2 additional experiments.