And number four is in some cases, changing the voltage difference can also actually close off these gap junctions. Now, why would we want to actually close off a gap junction? Well, let's suppose we have two cells which are connected by these gap junctions, and one of the cells is damaged in some way and ends up dying. So to basically prevent a second nearby healthy cell from being damaged, that dying cell will want to close off these gap junctions. And that's exactly where these different processes come into play to close off that gap junction. Now, finally, let's move on to the functionality of gap junction.