Northern blot analysis and flow cytometric analysis of FL5.12 cells. (A) Northern blot analysis for the IL-3 receptor. Total RNA was extracted from FL5.12 cells that had been transfected with the empty vector (lanes 1-4) or pMT-TEF (lanes 5-8) and cultured in the presence of IL-3 with Zn for the indicated periods of time. The blot was hybridized with mouse cDNA probes specific for IL-3 receptor β chains and α chain. The 28S rRNA visualized with ethidium bromide staining is shown in the bottom panel. (B) Flow cytometric analysis for surface expression of the IL-3 receptor. FL5.12 cells transfected with the empty vector, pMT–E2A-HLF, pMT-TEF, or pMT-TEF/BX were cultured in IL-3–containing medium in the presence or absence of Zn for 24 hours. Cells were analyzed with the specific antibodies for mouse β_IL3, β_C, or α chains. Dotted or solid lines indicate the histograms of control staining, and filled curves indicate those of specific antibodies.