The cast of "Dancing With the Stars" season 21 is slowly being revealed. A few more celebrities will join Bindi Irwin in vying for the mirrorball trophy.

They are: TV chef Paula Deen, music legend Chaka Khan, Triple Crown-winning jockey Victor Espinoza, Backstreet Boy Nick Carter, and Vine star Hayes Grier.

If you're wondering what a "Vine star" is, Grier boasts a huge following on social media, with four million followers on Vine and 2.93 million on Twitter. He shared his good news on the latter, naturally:

ABC has been coy about unveiling the lineup for this season of "DWTS." The show earlier announced nine of the 12 pros, and has been trickling out celeb names. The full cast will be revealed on Sept. 2 on "Good Morning America."

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