PLPPR4 and schizophrenia: PRG‐1 is highly expressed in layer IV neurons of the somatosensory cortex and already 50% reduction of functional active PRG‐1 at the glutamatergic synapse caused reduced LPA uptake into postsynaptic neurons, and as a consequence, shifted E/I balance toward a higher excitability of cortical networks leading to pathological cortical information processing as observed in schizophrenia (Coyle, 2006; Belforte et al, 2010; Hasan et al, 2012a, 2012b; Yizhar et al, 2011).