In the study by Cynn et al. (2006), the cue was assisted using a biofeedback unit and the increase in gluteus medius muscle activity was associated with reduced lateral pelvic tilt angle. (strengthandconditioningresearch.com)
Hip abduction - adduction — Greater hip abduction leads to greater gluteus medius muscle activity during multi-joint hip extension movements (strengthandconditioningresearch.com)
The glute medius also plays a part in both internal & external rotation of the femur (turning the thigh bone toward or away from the body). (parduccifitness.com)