PDE4DIP and schizophrenia: Previous RNA-seq analyses of forebrain cortical neurons differentiated from a schizophrenia patient iPSC line with the 4-bp deletion in DISC1 gene (D2 line, Pedigree H; Supplementary Fig. 1a) revealed significant upregulation of multiple transcripts related to the PDE4 family, including PDE4A, 4C, and PDE4DIP (PDE4D interacting protein)14,16, when compared to neurons from a family control iPSC line without the DISC1 mutation (C3, Pedigree H) (Fig. 1a).