Expression profiles of the Epo-GFP transgenes with mutations in the promoter GATA sequence. (A) Sequences near the GATA factor–binding site in the promoter region of the mouse Epo gene. The wild-type GATA-box in the wt-Epo-GFP transgene was mutated to create the transgenes m1-Epo-GFP and m2-Epo-GFP. Capital T indicates the point 30-bp upstream from the transcription initiation site. Sections of kidneys (B-G), livers (H-J), and lungs (K-M) from the m1-Epo-GFP transgenic mouse line 1A (B,C,E,F,H,I,K,L) and wt-Epo-GFP transgenic mouse line WA (D,G,J,M) under normal (B,E,H,K) or anemic (C,D,F,G,I,J,L,M) conditions were stained with anti-GFP antibody (brown). The distal tubules (d) constitutively expressed the mutant transgene (E,F), but not wt-Epo-GFP (G). Arrows indicate the kidney interstitial cells, which expressed GFP only after the induction of bleeding anemia in both m1-Epo-GFP (F) and wt-Epo-GFP (G) transgenic mice. Arrowheads indicate the bile ducts, which were constitutively positive for GFP in the mutant Epo-GFP transgenic mice (H-I), but negative for GFP staining in the wt-Epo-GFP transgenic mice (J). Hepatocytes surrounding the central vein (*) expressed GFP only in anemic conditions in both m1-Epo-GFP (I) and wt-Epo-GFP (J) transgenic mice. The bronchial epithelium (★) was also positive for GFP antibody staining only in the mutant Epo-GFP transgenic mice (K,L). # indicates, interlobular triad. Scale bars are 300 μm (B-D), 20 μm (E-G), and 100 μm (H-M).