NRG1 and schizophrenia: Genes and proteins that have been linked to the regulation of spine morphology and development, such as Neuregulin-1 and ErbB4 or Cdc42, show aberrant expression or signaling in schizophrenia patients (Stefansson et al., 2002; Hashimoto et al., 2004; Hill et al., 2006; Pan et al., 2011).