RGS2 is repressed by activating Flt3 mutations. (A) Analysis of RGS2 mRNA levels by real-time RT-PCR. The 32D cells stably transfected with either wild-type Flt3 (Flt3-WT) or Flt3-ITD were growth factor starved for 12 hours. Samples were taken for RNA preparation at the indicated time points after the addition of IL-3 () or FL (▦). (B) RGS2 protein levels. The 32D cells stably transfected with Flt3-WT or Flt3-ITD were cultured for 12 hours in the absence of IL-3 and in the absence or presence of FL as indicated. RGS2 protein levels were determined by Western blot. (C) Flt3-ITD–induced RGS2 repression can be antagonized by inhibition of Flt3 phosphorylation. The 32D/Flt3-ITD cells were cultured in the presence of 100 nM SU11248 (▪), an Flt3-ITD–specific tyrosine kinase inhibitor. After 24 hours, cells were washed, one half was cultured further in the absence () and the other half in the presence of SU11248. RGS2 mRNA levels were analyzed by real-time RT-PCR.