The Insider.com

Paul Rudd, Leslie Mann, Iris Apatow and Maude Apatow played Katherine Heigl's kin in the 2007 hit Knocked Up and now This Is 40 -- a spin-off/sequel to that film -- pushes their nuclear family to the forefront.

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VIDEO - Katherine Heigl's Daughter Steals The Show

And let me tell you, there's a lot of between the leg action happening throughout the course of the two-minute trailer.

Also glimpsed is a lot of heart, some solid laughs (mostly courtesy of Melissa McCarthy's cameo) and the return of Jason Segel. I'm guessing he will reprise his Knocked Up character -- but for those fans wondering if that means we'll find out what happened to Ben and Allison after their baby was born, keep guessing because writer/director Judd Apatow just told a fan on Twitter that there would be no mention of Ben or Allison in the movie.

But he did add, "That story is for another time." So .... Knocked Up sequel anyone?

This is 40 opens December 21.