IL-3 enhances the transcriptional activity of endogenous RARs in EML cells.
(A) EML cells with or without overnight (15- to 18-hour) treatment with IL-3 were transfected with the RXR-RAR–responsive RARE tk-LUC reporter, and relative luciferase activity was determined in cell extracts after 5 hours of culture in the indicated concentration of ATRA. Calculated luciferase activity was normalized for transfection efficiency using a β-galactosidase reporter regulated by the β-actin promoter as described in “Materials and methods.” Results are the average of at least 3 independent experiments. (B) Western blot analysis of RXRα and RARα expression in the EML cells with or without overnight IL-3 and in EML/GM-CSF cells. (C) Relative luciferase activity of an RSV-luciferase reporter transfected into EML cells with or without overnight IL-3 and incubated for 5 hours in the presence or absence of ATRA (10−6 M). Results are the mean of at least 3 independent experiments.
