Fig. 4. Expression of one copy of Gli1 can rescue the Gli2 mutant floor plate defects. In Gli2 mutant embryos, the floor plate cells are missing (Fig. 2G-L). At E10.5, ectopic expression of one copy of Gli1 in the Gli2 domain results in rescue of the ventral spinal cord defect, as assessed by immunohistochemical staining for Shh, Nkx2.2 and Islet1/2 (A-C) or by X-gal staining in Gli2^1ki/lzki embryos (D-F). (A-C,F) Gli2^1ki/lzki embryos, (D) Gli2^lzki/+ embryo and (E) Gli2^lzki/lzki embryo. Red asterisk indicates floor plate that does not express lacZ from the Gli2 allele. The margins of the spinal cord and spinal canal are outlined by broken lines. Scale bar: 100 µm.