First detected at 16.5 dpc only in olfactory epithelium (OE) and the epithelium of the vomeronasal organ (VNO). At this stage, expression in OE is punctate and is restricted to only some of the sensory neurons. At birth and postnatally, expression in these organs extends to more neurons. At 3 weeks, expression shows a smooth gradation from high apical to low basal within the layer of mature olfactory sensory neurons of the olfactory epithelium.