The Jak2 inhibitor (AG490) inhibits the IL-3–induced enhancement of RAR transcriptional activity in EML cells.

The SCF-dependent EML cells were incubated overnight (15 hours) in the presence or absence of IL-3 (5 ng/mL) as indicated. Cells were then incubated for 60 minutes in the various chemical inhibitors (respective concentrations are noted in “Materials and methods”). The cells were then electroporated with the βRARE-tk-Luc reporter (25 μg) and the internal control β-galactosidase reporter (20 μg) and after electroporation the cells were maintained in the same inhibitors with or without IL-3 and with or without ATRA treatment (1 μM) as indicated. Five hours later, the cells were harvested and relative luciferase activity was determined on cell extracts as detailed in “Materials and methods.” Results represent the averages and SDs from at least 3 independent experiments.