Fig. 7. Endogenous Gli1 is not required when the Shh pathway is activated by ectopic Gli1. In Gli2 mutant spinal cords (A-D), Shh expression cannot be detected, Nkx2-2 expression is greatly reduced in the ventral midline, and the expression domains of Isl1/2 and Pax6 are shifted ventrally. When Gli1 is expressed from the endogenous Gli2 locus in Gli2^1ki/1ki embryos, the Gli2 mutant defects are rescued and Shh signaling is restored (E-H). Removal of endogenous Gli1 does not alter ventral spinal cord patterning in Gli1^lz/lz;Gli2^1ki/1ki embryos (I-L). Arrowhead indicates ventral limit of Pax6 expression domain. Scale bar: 50 µm.