Flash - How To Target URLs In AS3

How would you add a target="_self" function onto the buttons in this actionscript (as3) I need the buttons to open within the same browser window and not a new (_blank) window:

skype_btn.addEventListener(MouseEvent.MOUSE_DOWN, mouseDownHandler);
function mouseDownHandler(event:MouseEvent):void {
navigateToURL(new URLRequest("skype:mySkypeIdentifier"));
} email_btn.addEventListener(MouseEvent.MOUSE_DOWN, mouseUpHandler);
function mouseUpHandler(event:MouseEvent):void {
navigateToURL(new URLRequest("mailto:myEmailAddresss@myDomain.com?subject=rts
Esolutions enquiry"));
}