Knockdown of dicer-1 leads to accumulation of nonsynaptic GluRIIA and GluRIIB protein. The top panels show representative confocal micrographs generated from image stacks of ventral longitudinal muscle 6/7 NMJs stained using antibodies against GluRIIA (green), GluRIIB (red), and HRP (blue). In control NMJs, GluRIIA and GluRIIB protein is incorporated into multimeric GluRs that are localized almost exclusively at NMJs (marked with anti-HRP; blue). When dicer-1 RNAi is expressed in postsynaptic muscle cells (24BGal4/UAS–dicer-1.RNAi), the muscle cells show abundant nonsynaptic GluRIIA and GluRIIB immunoreactivity. Three vertical bands pass through the micrographs. These bands each show only fluorescence in one channel: green (GluRIIA), red (GluRIIB), or blue (anti-HRP; left to right, respectively), as grayscale images. Synaptic and nonsynaptic GluR immunoreactivity is quantified on the bottom. The amount of synaptic GluRIIA and GluRIIB is not significantly changed by muscle knockdown of dicer-1, but the amount of nonsynaptic GluRIIA and GluRIIB is increased 300–600% (n = 12 for each genotype). Error bars represent SEM. n.s., not significant. **, P < 0.001; ***, P < 0.0001.