ERBB4 and schizophrenia: Experimental studies showed that both downregulating (Rimer et al. 2005; O’Tuathaigh et al. 2007; Bian et al. 2009; Van Den Buuse et al. 2009) and upregulating (Deakin et al. 2009; Kato et al. 2010) NRG1–ErbB4 signaling-induced schizophrenia-like abnormal behavior.