Fig. 4. Mutants that mimic permanent serine phosphorylation of -synuclein exhibit reduced transport in rat cortical neurons. -Synuclein mutants that mimic permanent states of phosphorylation (S87D, n=124 neurons, and S129D, n=56 neurons) or dephosphorylation (S87A, n=50 neurons, and S129A, n=53 neurons) of human -synuclein, or wild-type human -synuclein (WT, n=124 neurons) were transfected into 5 DIV rat cortical neurons. Bars represent mean rate of transport (µm hour^–1) ± s.e.m. for each protein between 3 hours and 6 hours after glycerol shock. Transfection of the phosphorylation mimics of -synuclein, S87D or S129D, resulted in statistically significant reductions in the rate of transport compared to wild-type -synuclein (^*P<0.001).