Fig. 1. Conditional expression of GATA-2 and EGFP. (A) Constructs of GATA-2/IRES–EGFP and control IRES–EGFP. TetO stands for the tetracycline-responsive element. (B and C) FACS and western blot analyses of the time course of EGFP and GATA-2 expression in ES cells after being deprived of tetracycline. (D) Morphological change of ES cells by depriving them of tetracycline. (E) Expression of primitive endoderm differentiation markers, HNF-4 and collagen type IV, 4 days after the expression of GATA-2, GATA-1 and activated GATA-2/ER. Expression of GATA-2 and GATA-1 was induced by depriving the cells of tetracycline. The activated GATA-2/ER was obtained by depriving the cells of tetracycline and by the addition of β-estradiol (βE). The primer set for collagen type IV was used for the RT(–) control. (F) Expression of EGFP in TER-119-expressing erythroid cells induced from ES cells. The cells were deprived of tetracycline from day 5 of induction and the data were obtained 3 days later.