Interestingly, both schizophrenia and control subjects carrying a schizophrenia-risk associated variant within the TCF4 gene and mice moderately overexpressing TCF4, a transcription factor downstream of PKA signaling, (Figure 2) also have disrupted PPI activity (Brzózka et al., 2010 and Quednow et al., 2014). This evidence concerns the gene TCF4 and schizophrenia.