School may be out for summer vacation in most parts of the country, but kids will be heading back to university this weekend -- Monsters University, that is. With a second-week gross of around $45-50 million, the Disney/Pixar animated feature is expected to easily hold off challenges from White House Down and The Heat. The only question appears to be, which film will wind up in second place. Box office analysts are calling it a toss-up. Despite the fact that the movie's plot -- about foiling an attack on the White House -- is substantially similar to last March's Olympus Has Fallen its two stars, Channing Tatum and Jamie Foxx, have scored strongly at the box office over the past year and director Roland Emmerich has a solid reputation for delivering at the box office. On the other hand, theater marquees will also be displaying the names of two popular actresses who are starring in the comedy The Heat, Sandra Bullock and Melissa McCarthy. And director Paul Feig was also the man behind the camera for Bridesmaids, one of the biggest comedy hits of recent years. Each film is expected to take in around $35-40 million. (While that figure would represent success for The Heat, it would constitute a setback for Sony, which reportedly spent $150 million to produce White House Down.) World War Z with around $30-35 million and Man of Steel with about $20-25 million are expected to round out the top five.