Rotating object, how to stop on rollover?

1

im doin some circles rotating like a wheel, script as below,
but i duno how to make it stop while i mouseover on the circles…
anyone pls help me? thx thx…

this is the script i put on the circle object:

onClipEvent (load)
{
radius = 40;
degrees = 0;
}
onClipEvent (enterFrame)
{
angle = degrees * 0.017453;
degrees = degrees + 1;
xposition = radius * Math.cos(angle);
yposition = radius * Math.sin(angle);
this._x = xposition + _root.center_cross._x;
this._y = yposition + _root.center_cross._y;
}

on (release){
_root.bg_color.gotoAndPlay(“red”);
_root.gotoAndPlay(“msg”);
}