While mice heterozygous for the Shh::gfp allele are viable, fertile, and indistinguishable from wild-type littermates, homozygotes are stillborn and show developmental defects consistent with reduced Sonic Hedgehog (Shh) signaling. The Shh::gfp mutation has GFP inserted into the endogenous Shh processing site (and adds a new processing site after the GFP). Thus normal Shh processing leads to secretion of the GFP-tagged Shh signaling ligand (N-Shh::GFPp) instead of wild-type Shh; with N-Shh::GFPp retaining both GFP and lipid modifications post-processing. Biochemical and cellular analysis indicates that Shh::GFP undergoes correct processing to produce active, bi-lipidated signaling peptides. Shh::GFP processing is, however, less efficient and results in reduced levels of Shh::GFP compared with wild-type Shh protein. These Shh::gfp mice produce bioactive, fluorescently labeled Shh from the endogenous Shh locus and may be useful to directly visualize the function of Shh ligand in an in vivo context, such as during neural tube patterning. In addition, these mice may also be useful in conjunction with other Sonic Hedgehog (Shh) mutant strains including Shh knockout mice (Stock No. 003318), Shh-floxed mice (Stock No. 004293), Shh-GFP/cre mice (Stock No. 005622), and Shh-creERT2 mice (Stock No. 005623). The Jackson Laboratory 2024, used with permission.