Positive feedback plays a key role in the ability of signaling molecules to form highly localized clusters in the membrane or cytosol of cells. Such clustering can occur in the absence of localizing mechanisms such as pre-existing spatial cues. diffusional barriers. or molecular cross-linking. http://www.roneverhart.com/Bernhardt-Arctic-6-seater-Dining-Table-with-Glass-Top-Acrylic-Base/