Fig. 1.
Activation of conditional GATA-1 in G1E-ER2 cells triggers terminal erythroid maturation. Conditional GATA-1 was created by fusing the full-length murine cDNA to the ligand-binding domain of the human ER. G1E-ER2 cells are a clone derived from stable expression of the GATA-1/ER chimeric protein in the GATA-1−erythroid cell line, G1E. (A) Kinetics of G1 cell cycle arrest (left) and hemoglobin accumulation (benzidine staining, right) after addition of estradiol. Note that estradiol has no cell-cycle–arresting or hemoglobin-inducing effects on the G1E parental line, which does not express estradiol-inducible GATA-1. (B) G1E-ER2 cell morphology (May-Grünwald-Giemsa staining, top panels) and benzidine staining (bottom panels) before and 72 hours after addition of estradiol. Original magnification: 1,000× top panels; 400×, bottom panels. (C) Northern blot analysis of erythroid-expressed genes. Each lane contains 15 μg of total RNA.