GAP43 and schizophrenia: In a pioneering study using immunohistochemical approaches, Arnold and colleagues reported a reduction in p75 nerve growth factor receptor (p75NGFR)-positive basal cells and an increase in growth-associated protein 43 (GAP43)-positive immature OSNs in the postmortem OE tissue of patients with schizophrenia, suggesting altered developmental composition of the OSNs [47].