Acts as an inhibitor of dendrite extension and branching. Expressed in brain, kidney and lung. In the telencephalon, expressed in the piriform cortex, hippocampus and olfactory bulb. In the diencephalon, expressed in the dorsal thalamus. Expressed in Purkinje cells of the cerebellum and in numerous medullary nuclei. Expressed in embryo at 8.5 dpc onward. In the neural plate, expressed in the presumptive forebrain and midbrain and in rhombomere at 4 and 8.5 dpc. Expressed in the limb buds and in the ectoderm of the first branchial arches at 9.5 dpc. In the brain, expressed in the dorsal mesencephalon (tectum) and prosencephalon (presumptive isocortex) at 9.5, 10.5 and 11.5 dpc. In the cortex, expressed in dorsolateral patch of the neuroepithelium at 10.5 dpc. Expressed in the ectoderm of the branchial arch and the oral ectoderm at 10.5 dpc. In the limbs, expressed in the apical ectodermal ridge at 11.5 dpc. Expressed in the telecephalon, ventricles, diencephalon and medulla oblongata at 12.5 dpc. Expressed in the neural tube, cochlear ganglion and olfactory bulb at 14.5 dpc. In the kidney, lung and intestine, expressed in epithelial cells at 14.5 dpc. Up-regulated by Notch. Glycosylated. Undergoes proteolytic cleavage. Knockout mice for this gene exhibited an increase in dendrite extension and branching of pyramidal neurons in the CA1 region of the hippocampus. Belongs to the FJX1/FJ family.