Whenever I think of that fourth quarter, my main memory is early in the quarter, the Blazers up 15 and the Lakers missing a shot--Brian Grant has position and seemed to have the rebound. Then Shaq ripped the ball out of his hands and went back up and scored. Probably unfairly, I've always thought of that as the turning point in the game. Grant secures that rebound and the Blazers have the ball with a 15 point lead and all the momentum. Instead, it's an instant 2-4 point swing and the Lakers get some momentum.
Lots and lots of other stuff had to happen, like the Blazers basically missing every shot from then on out, but for some reason that moment seems most significant to me.