Which Browser does SoapUI Pro use?

We are testing an application that will not allow the user to log into when using IE 8, but it does work with IE 9 up.
The only thing that the user can do in IE 8 is get to the log in page.
I unistalled IE 8 and installed IE 11 and now I can log in through the browser, but not through SoapUI Pro.

How does SoapUI (now using NG 1.1) know what to use? IE 8, IE 9, ... or does it use the IE engine of the install IE version on the PC?