The inositol 1,4,5-trisphosphate (IP3) receptor (IP3R) acts as a Ca2+ release channel on internal Ca2+ stores. Type 1 IP3R(IP(3)R1) is enriched in growth cones of neurons in chick dorsal root ganglia. Depletion of internal Ca2+ stores and inhibition of IP3 signaling with drugs inhibited neurite extension. Microinjection of. heparin, a competitive IP3R blocker, induced neurite retraction. Acute Localized Loss of function of IP(3)R1 in the growth cone induced by chromophore-assisted Laser inactivation resulted in growth arrest and neurite retraction. IP3-induced Ca2+ release in growth cones appears to have a crucial role in control of nerve growth.