C-myc expression is lost in the CNS in Shh/Gli pathway mutants. A) c-myc is normally expressed in the optic tectum (black arrowhead) and the developing eye. Strong expression is also detected in the liver (white asterisk). B) smu mutant embryos show no expression of c-myc in the CNS. C) dtr embryos have no c-myc in the eye (black arrow), tectum and liver. D) yot embryos still show labelling for c-myc, although reduced; in both the eye and optic tectum labelling is preserved. Liver also retains some c-myc labelling. All lateral views are dorsal up, anterior left.