Indian hedgehog (IHH) is an essential signaling factor that is secreted in the gut, cartilage, and bone during embryonic development. IHH acts through the patched (PTC) receptor to induce transcriptional changes important for bone and cartilage development. IHH also induces the expression of parathyroid hormone-related peptide (PTHrP), which in turn mediates IHH activity during chondrocyte differentiation, forming a negative feedback loop.