Pause a specific function when another button is clicked

Hi,

I am going to make a slider with three image. its working fine. but when I click circle button it working in both new function(fisrtslideClick, secondSlideClick, thirdSlideClick) and previous function(fisrtslide, secondSlide, thirdSlide). I need to pause the specific previous running function(fisrtslide/secondSlide/thirdSlide) when I click the specific circle.

I am looking for your help.

Here is my code:

function fisrtslide():void {
background_Two.visible = false;
background_Three.visible = false;
background_One.visible = true;
background_One.mask = mc_circle;
animation();

TweenLite.delayedCall(4, secondSlide);        

}

function fisrtslideClick(event:MouseEvent):void {
fisrtslide();
}

function secondSlide():void {
background_One.visible = false;
background_Three.visible = false;
background_Two.visible = true;
background_Two.mask = mc_circle;
animation();

TweenLite.delayedCall(4, thirdSlide);        

}

function secondSlideClick(event:MouseEvent):void {
secondSlide()
}

function thirdSlide():void {
background_One.visible = false;
background_Two.visible = false;
background_Three.visible = true;
background_Three.mask = mc_circle;
animation();

TweenLite.delayedCall(6, fisrtslide);    

}

function thirdSlideClick(event:MouseEvent):void {
thirdSlide();
}

fisrtslide();

firstSlideBtn.addEventListener(MouseEvent.CLICK, fisrtslideClick);
secondSlideBtn.addEventListener(MouseEvent.CLICK, secondSlideClick);
thirdSlideBtn.addEventListener(MouseEvent.CLICK, thirdSlideClick);