ERBB4 and glioblastoma: Karbownik and colleagues showed that in glioblastoma cells, and at a dose comparable to ones considered efficacious, clozapine, olanzapine, and quetiapine decreases the mRNA expression of phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit delta (PIK3CD), a gene encoding for the delta catalytic subunit of PI3K by going on to alter the ErbB4-PI3K pathway [424].