Hi Akiko:

I had a chance to look over this in more detail, and I suggest the following:

While McGee (2006:16) states "violence has played an important role in the U.S. national ideology, particularly through the myth of the frontier," this is a broad assumption on the whole of American ideology, which, to many, remains undefined. However, it is clear that violence has played an important role in Western film."

Please let me know if you have any other questions.

Thanks,
EditPro