Olfactory sensory neurons contain olfactory receptors, which are G protein-coupled receptor proteins that localize to the cilia and display affinity for and bind to a variety of odor molecules. Olfactory neurons send their axons from the olfactory epithelium to the olfactory bulb, which is covered by the CNS basal lamina. FEZF1 (Fez family zinc finger protein 1), also known as Forebrain Embryonic Zinc Finger and Zinc finger protein 312B, is a 475 amino acid nuclear protein that is expressed in the olfactory epithelium and hypothalamus of mice. In FEZF1-deficient mice, axons of olfactory neurons do not reach the olfactory bulb, suggesting that FEXF1 is required for the penetration of olfactory axons though the basal lamina before innervation of the olfactory bulb. When FEZF1 translocates to the nucleus, it induces KRAS overexpression, resulting in activation of ERK-signaling. Overexpression of FEZF1 leads to accelerated proliferation in cultured cells and increased tumor mass in mice. There are three isoforms of FEZF1 that are produced as a result of alternative splicing events.