Rob Lowe, Ryan Seacrest & More Stars Attend iHeartRadio Music Festival 2017!

Rob Lowe and Ryan Seacrest are having a blast at the 2017 iHeartRadio Music Festival in Las Vegas on Friday (September 22)!

The stars were all spotted mingling backstage, taking pictures on the red carpet and entertaining the hyped crowd onstage at the two-day music event happening at the T-Mobile Arena.

Rob posed alongside his sons Matthew and John Owen on the red carpet.

Heidi Klum, James Van Der Beek, Scott Michael Foster, James Maslow, Vella Lovell and Jared Leto, who still has his beard, were also spotted hanging out at the music festival.

15+ pictures inside from the iHeartRadio Music Festival…