In vivo characterization of G-F-DD regulation and activity. Lentiviral vectors expressing either C-terminal fusion of YFP and DD (YFP-DD), GDNF or G-F-DD were delivered to the striatum of rats. One group of G-F-DD animals were treated with TMP. Three weeks after treatment, part of the YFP-DD and G-F-DD groups were processed for histology and the remaining animals for GDNF ELISA. (a) Immunohistochemistry for GDNF and p-rpS6. Scale bars: first row, 500 µm; second row, 100 µm. (b) GDNF ELISA for untransduced (Unt) GDNF, YFP-DD, and G-F-DD groups. Two-way ANOVA with Bonferroni multiple comparison test (**P < 0.01) (n = 5). (c) Relative quantification of the number of p-rpS6 cells, using the contralateral side as control. Unpaired t-test (*P < 0.02) (n = 3). DD, destabilizing domains; GDNF, glial cell line–derived neurotrophic factor; YFP, yellow fluorescence protein.