Possible to tween a mask?

[Billy Williamton]

I want to add a circle mask to a sprite and tween (animate the mask to shrink or grow) it.  Is this possible?

function preload() {    game.load.image('lgC', 'circle.png');}function create() {    lgC = game.add.sprite(game.world.centerX, game.world.centerY, 'lgC');    lgC.anchor.set(.5, .5);    // Draw mask    var maskG = game.add.graphics(0, 0);    maskG.beginFill(0xfffff);    maskG.drawCircle(0, 0, 300);        //Want to add mask to lgC and be able to tween the mask.}