Indian hedgehog (IHH) is one of three proteins in the hedgehog family which includes sonic hedgehog and desert hedgehog. Hedgehog proteins are important signaling molecules, acting through patched and smoothened receptors. During embryonic development, they are expressed in the fetal lung, gut, stomach, liver, kidney, and pancreas. IHH is strongly expressed in cartilage and regions of developing bone, and its signaling regulates growth and differentiation of bone tissue (Marigo et al.; Valentini et al.; St-Jacques et al.). IHH is also involved in yolk sac vasculogenesis, indicating a role in the differentiation of epiblast cells into endothelial and red blood cells (Byrd et al.). IHH induces the expression of parathyroid hormone-related peptide (PTHrP), which negatively regulates IHH during chondrocyte differentiation and proliferation (Vortkamp et al.).