max in WT synaptoneurosomes, suggesting that Src signaling could be downregulated in KI synapses. On the flip side, our ability to rescue SERT functionality in KI midbrain synaptoneurosomes with the inhibition of FAK signifies elevated FAK signaling downstream of the Pro32Pro33 mutant, as confirmed by increased pFAK localization in 5-HT synapses. O