COOK pasta as directed on package, omitting salt.
MEANWHILE, cook chicken in large skillet sprayed with cooking spray on medium heat 5 min., stirring occasionally. Add vegetables; cook 3 to 5 min. or until chicken is done and vegetables are crisp-tender, stirring occasionally.
DRAIN pasta. Add to chicken mixture with spaghetti sauce; stir. Cook 5 min. or until heated through, stirring occasionally. Top with cheese; cover. Remove from heat. Let stand 2 to 3 min. or until cheese is melted.