PGGT1B and schizophrenia: The GGTase I β subunit PGGT1B was decreased 13% (W = −77, p = 0.004) and the Rab protein-specific GGTase II β subunit RABGGTB was decreased 8% (t(12) = 2.29, p = 0.04) in schizophrenia (Fig. 1).