Prodigy, one half of Mobb Deep, has died in Las Vegas

For years, he's battled heath problems to include sickle cell, but right now the cause of death is unknown.

Prodigy was in Vegas over the weekend performing with the "Art of Rap" tour ... with ,  KRS-One, Ice-T ,Onyx, Ghostface Killah and more. Mobb Deep performed Saturday night.