Fig. 4.

GATA1 controls the expression of Th2 cytokines in mast cells. (A) A reporter gene assay was done with IL-4 and -5 promoters by using the MC9 mast-cell line. The mean values, with standard deviation, of relative luciferase activity of four different experiments are shown. (B) MC9 cells were infected with retrovirus encoding GATA1 or -2 bicistronically with EGFP. GFP-positive infected cells were enriched by cell-sorting and stimulated with PMA (25 ng/ml) plus ionomycin (500 nM) for 18 h. Quantitative real-time RT-PCR was performed. (C) Inhibition of Th2 cytokine expression by the introduction of siRNA for GATA1. BMMCs were transfected with siRNA specific for GATA1. Two days after transfection, the cells were stimulated with PMA plus ionomycin, and transcriptional levels of GATA1 and Th2 cytokines were determined by quantitative RT-PCR. Two experiments were done with similar results.