Decreased AML1-ETO protein abundance upon corticosteroid treatment. (A) Kasumi-1 immunoblot with anti-AML1 antibody. AML1-ETO protein loss was seen upon treatment with methylprednisolone (MPD) or dexamethasone (DEX) for 48 hours. AML1-ETO protein expression was only minimally decreased in the methotrexate (MTX)–treated samples. (B) Methylprednisolone reduces cellular viability and AML1-ETO abundance in primary patient t(8;21) cells. Primary patients' cells were treated with methylprednisolone, and cellular viability was assessed at 3 days with an ATP-based assay and plotted as a ratio relative to control cells. Error bars denote SD across 5 replicates. At 48 hours, expression of AML1-ETO was assessed with immunoblot using an anti-ETO antibody. AML1-ETO loss was seen upon treatment with methylprednisolone. (C) Minimal change in AML1-ETO RNA expression is seen upon MTX and MPD treatment for 48 hours. Results are normalized to control ABL1 gene expression, and conditions were tested in quadruplicate. (D) Methylpredisolone-induced AML1-ETO protein loss was rescued with both MG132 and RU486. Cells were treated with methylprednisolone ± RU486 for 48 hours. MG132 was added for the final 30 minutes of incubation.