It is school dependent, and many people would say that your numbers are only useful to decide whether you'd be extended an interview, and that being invited means that you've passed the "screen".
However, keep in mind that when (/if) a school does a holistic review of a candidate, everything is taken into account, and that includes scores (although the weight placed on them may be considerably less). That's not to say that a below-median MCAT is a death sentence; it's called
holistic because your MCAT is not in a vacuum (although extremes certainly detract from your entire app). Thus, I think it'd be wrong to say that your MCAT becomes completely irrelevant, but again, it is school-dependent. That being said, most (probably all) schools that you interview at are okay with your MCAT, and would seriously consider you for admittance, or else they wouldn't have invited you to interview.
There are occasional horror stories (unverifiable without proof) of students having been rejected post-interview due to poor MCAT scores. I believe that more-often than not, this is due to schools receiving re-take scores
after the interview, with the student showing no/little/negative improvement. More commonly, it's just being up against a tough group of applicants where the rest of your application doesn't go to bat for you as much as you need it to.
@Goro ,
@LizzyM , and
@gyngyn could probably give you a more accurate answer, although they have discussed this in other (recent) threads that you can search for.
Edit: when I say MCAT, I really meant MCAT + GPA (numbers). I just forgot and wrote only MCAT, so replace "MCAT" with "numbers", because I'm too damn lazy to do it.