Expression of GATA factors in renal tubular cells and binding of the Epo gene to the GATA box promoter. (A,B) Immunohistochemical staining of GFP in the kidney of a Gata2-GFP knock-in mouse. (C,D) X-gal staining in the kidney of a Gata3-LacZ knock-in mouse. (E,F) Immunohistochemical staining with anti–GATA-4 antibody in the kidney of wild-type mouse. Note that the distal tubules (d) and collecting ducts are positive for both Gata2-GFP (brown) and Gata3-LacZ (blue), but negative for GATA-4. On the other hand, the expression of Gata2-GFP and GATA-4 was detected in REP cells (arrows in B,F). (G) Chromatin immunoprecipitation (ChIP) assays of GATA-2 and GATA-3 and the Epo promoter. Chromatin complexes from the normal renal medulla were immunoprecipitated with anti–GATA-2 or anti–GATA-3 antibodies and the presence of Epo, Aqp2, and Gata1 gene promoter fragments was examined by PCR. Preprecipitated samples (input) were used as the internal positive controls for PCR. Normal rabbit immunoglobulin G (IgG) was used as a negative control. Scale bars are 300 μm (A,C,E) and 20 μm (B,D,F).