(A) Treatment of rat mesencephalic neurons with 120 nM Tat for 15 min, 30 min, or 24 hours, caused significant increases in DAT specific DA uptake versus vehicle control at 30 minutes (# p < .02) and 24 hours (* p < .04) (two-tailed unpaired t-test). No significant differences in vehicle control, versus 120 nM heat-inactivated Tat control, have been found for DAT uptake activity or membrane DAT levels (Figures S1, 4, 5, and unpublished data), demonstrating specificity of Tat’s effects on DAT activity. For each condition (i.e. ± Tat), non-DAT specific DA uptake in the presence of the DAT specific antagonist GBR-12909 was subtracted from total uptake (i.e. ± Tat without GBR-12909) to generate DAT-specific uptake displayed. To facilitate comparisons across groups and to subsequent immunoblot data (Figure 1B), the mean 3H-DA uptake count per minute (CPM) ± SEM values of each time-matched control group were normalized to “100”. N=4. (B) Despite a large increase in DA uptake at 30 minutes of 120 nM Tat, total DAT protein levels did not change at this time point. By 24 hours 120 nM Tat treatment, the increase in total DAT protein (190% ± 18%; *p < .04 vs. time-matched control; two tailed paired t-test) was similar to the increase in DA uptake at this same time point (187 ± 21 normalized CPM; *p < .04 vs. time-matched control; two-tailed unpaired t-test) (Figure 1A, 24 hour Tat treatment). Equal total protein amounts were loaded (Bradford Assay), and a non-specific band was used as loading control (Ditzel et al., 2003; Lin et al., 2007). Following background correction, integrated band densities were averaged across several blots and expressed in graphical form ± SEM. Images represent sample bands for the bar immediately below each band image. N=3.