What the two pronouns stand for?

What the two pronouns stand for?

The passage below is from Jellyfish age backwards by Nicklas Brendborg.

This garbage/recycling system – and others like it – actually unites everything we have discussed so far. For one, autophagy is what awaits us at the bottom of our rabbit hole. We started at growth hormone being released from the pituitary gland. ##077 Upon reaching the liver, we learned that growth hormone promotes production of IGF-1. And when IGF-1 binds to cell receptors, it activates the protein complex mTOR. Now, to be fair, mTOR does a lot of things, many of which impact health. But the thing that is most obviously tied to ageing is that mTOR controls the cellular garbage collection system. Specifically, when mTOR is active, it blocks autophagy. And in turn, all the growth-promoting signals that activate mTOR/ do the same thing. So when rapamycin blocks mTOR, it essentially blocks the blocker, cancelling it out. This might sound a little confusing, but the bottom line is that blocking growth signals ends up activating autophagy. As a result, rapamycin only prolongs the life of laboratory organisms as long as autophagy is functional. If autophagy is broken, rapamycin stops working. So it really does seem like we have reached the end of this whole thing.

In this passage I want know what the two ‘it’s refer to individually.

Let me tell you my unproven answers.

The first ‘it’ seems to refer to ‘rapamycin’. (Am I right?)

And the last ‘it’ seems in one way to refer to ‘the blocker’. But in another the last ‘it’ seems to refer to ‘to block autophagy’. I am not sure which one is better or it’s just that I am wrong altogether.

Thanks in advance.