Robert Pattinson, Kristen Stewart, and Taylor Lautner not presenting at the MTV Movie Awards?

2009 MTV Movie Awards - AP Photo

The Twilight series has been chosen in several of the 2010 MTV Movie Awards' pre-nomination nominations (see here). Last year, to promote The Twilight Saga: New Moon, a large portion of the cast attended, and Robert Pattinson, Kristen Stewart, and Taylor Lautner all presented the first teaser trailer for the film during the show.
For the 2010 Awards, which air on June 6th, none of the cast is listed on MTV's roster of presenters, particularly "the big three" as pointed out by HitFix.