We've been neglecting this question for a long time, because we didn't want to present too much information all at once, and there wasn't any pressing need early on to show this. However, we'll show you now.

MDMA enters the serotonin axon terminal by going through the uptake transporters! Researchers say MDMA has a greater affinity for the transporter than serotonin (just like prozac does). This means that the MDMA will be the first thing to get into the axon terminal. Once there, it interacts with the vesicle, causing it to pour it's serotonin into the synapse. The important thing to be aware of is that the MDMA does its thing only after entering the serotonin axon terminal via the uptake transporters. This is important, as we will soon see.