3′ UTRs of Actα, Actβ, and Actγ drive local translation of reporter mRNAs in axonal growth cones and branch points. (A) Scheme of reporter constructs with coding sequence of myristoylated eGFP and respective 3′ UTRs of actin isoforms. (B) Representative time-lapse images from FRAP in growth cones of eGFP^myr-3′ UTR–expressing motoneurons. eGFP^myr was bleached and fluorescence recovery was monitored in defined regions of interest within the growth cone indicated in red circles. Quantification of FRAP shows 60% recovery of fluorescence signals in growth cones of motoneurons expressing eGFP^myr-3′ UTR of Actα (C), eGFP^myr-3′ UTR of Actβ (D), and eGFP^myr-3′ UTR of Actγ (E), and recovery is decreased after anisomycin and cycloheximide treatments (***, P < 0.001). (F) Representative time-lapse images of FRAP sequences of branch points in the distal axon. (G and H) Quantification of FRAP in defined ROIs within branch points (indicted in red circles) shows a faster recovery for eGFP^myr-3′ UTR of Actα in the first 20 min after bleach compared with eGFP^myr-3′ UTR of Actβ (*, P < 0.05; **, P < 0.01) and eGFP^myr-3′ UTR of Actγ (*, P < 0.05). Statistical analysis was performed by two-way ANOVA with Bonferroni post hoc test. Bar, 10 µm.