NOS1 and major depressive disorder: The carboxy‐terminal PDZ ligand of nNOS (NOS1AP, also named CAPON), a scaffolding protein of nNOS that indirectly binds to NMDARs, is a risk factor in many neurological diseases, such as schizophrenia, autism, bipolar disorder, post‐traumatic stress disorder, and depression (Candemir et al., 2016; Courtney, Li & Lai, 2014).