(**a**) Fraction of mobile PSD puncta in interneurons transfected with PSD-95-GFP and RFP (control) or PSD-95-GFP, RFP and respective short hairpin RNA (shRNA) constructs. Two additional methods for inhibiting dynein-based mobility were also included (treatment with 1 mM erythro-9-[3-(2-hydroxynonyl)] adenine (EHNA) and dynamitin transfection). PSD mobility was suppressed by LIS1 or NDEL1 shRNA and rescued by overexpression of RNAi-insensitive LIS1 and NDEL1 mutants ('LIS1 RNAi+mLIS1' and 'NDEL1 RNAi+mNDEL1'). Mutant LIS1 and NDEL1 RNAi constructs containing three mismatched nucleotides ('mLIS1 RNAi' and 'mNDEL1 RNAi') did not suppress PSD mobility. Both EHNA treatment and expression of dynamitin suppressed PSD mobility. (*n*=18 cells for control, *n*=6 cells for LIS1 RNAi, *n*=7 cells for mLIS1 RNAi, *n*=6 cells for LIS1 RNAi+mLIS1, *n*=8 cells for NDEL1 RNAi, *n*=5 cells for mNDEL1 RNAi, *n*=5 cells for NDEL1 RNAi+mNDEL1, *n*=5 cells for EHNA treatment, *n*=5 cells for dynamitin transfection.) Significant differences (one-way analysis of variance (ANOVA) followed by Tukey–Kramer multiple comparison tests): **P*<0.05. (**b**) Time-lapse imaging of an interneuron expressing PSD-95-GFP with NDEL1-KillerRed before and after CALI (within 60 min after irradiation). Arrowheads indicate the position of a PSD-95-GFP punctum. Scale bar, 5 μm. (**c**) Suppression of PSD mobility by CALI of NDEL1-KillerRed. The effect of CALI on the mobile fraction was significant at 5–50 min after CALI (53±13.4%, *n*=6 cells). The fraction of motile PSD-95-GFP puncta returned to the control level at 60–105 min after CALI (91±15.6%, *n*=6 cells). The mean velocity of mobile PSD puncta also decreased after CALI and this effect was sustained for more than 60 min (2.8±0.30 μm h^{−1} before CALI, 1.1±0.17 μm h^{−1} at 5–50 min after CALI, 1.9±0.24 μm h^{−1} at 60–105 min after CALI, *n*=6 cells). Significant differences (one-way ANOVA followed by Tukey–Kramer multiple comparison tests): **P*<0.05. All numeric data are mean±s.e.m.

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