VIDEO : Rob Kardashian's Ex Adrienne Bailon Reunites With Some of the Kardashian Klan

Kourtney Kardashian, 36, and Kylie Jenner, 18, were recently spotted hanging out with Adrienne Bailon, their brother Rob Kardashian's ex-girlfriend. "Reunited best friends lol," Kourtney said on Instagram Sunday, alongside a photo of her and Bailon, 32, sitting on Kylie's lap. "Cause we are sistersss," Kylie wrote , alongside another pic. Bailon also posted Kylie's photo, captioned with three heart emojis. The couple split in 2009 after a two-year relationship. Rob, 28, is currently dating Black Chyna, 27.