Jon Jones' NFL star brother, Arthur Jones , has been suspended 4 games for violating the league's PED policy ... this according to Ian Rapoport.
The Indianapolis Colts defensive end will be suspended WITHOUT PAY. He'll return to action on October 3rd.
Of course, Jon was also popped for PEDs recently ... and faces a 2 year ban from the UFC.
Jon says he's not a cheater and vows to prove it.
So far, no comment from Arthur.