Problem of Comprehending

As an ESL student, sometimes I could not clearly comprehend some sentence, for example:

The embryonic stem cell, a holy grail for cell and developmental biologists, has become the subject of a more controversial quest over the last few years as some policymakers have clamored to ban its use and alternative sources of stem cells have been uncovered.

The problem is that I could not get this clearly -- "...to ban its use and alternative sources of stem cells have been uncovered".

To ban what? (1) To ban "its use"; (2) To ban " alternative sources of stem cells".

I guess you would say, no, (1) is right while (2) is wrong. But my vague defense might be " alternative sources of stem cells have been uncovered" may mean " alternative sources of stem cells (that) have been uncovered" -- that is, "that" has been intentionally ignored.

My sense tells me I should admit "(2) is wrong". But, how can I get it very clearly in grammatical analysis?

Thank you in advance.

PS. If the orginal content "... as some policymakers have clamored to ban its use and alternative sources of stem cells have been uncovered" can be rewritten like this:
... as some policymakers have clamored to ban its use. But, alternative sources of stem cells have been uncovered.
It would be very clear and wouldn't get misunderstood. (At least for an ESL student).