DLG4 and glioma: To validate the pHluorin strategy, we confirmed that exposure of glioma cells expressing GluA2(Q)–SEP and PSD95–RFP to acidic medium (pH 5.5) quenched the signal, demonstrating that the majority of the AMPAR fluorescent signal at the postsynaptic puncta is from plasma membrane-bound GluA2 (Fig. 3i,j).