So the sheet is now exposed to a chemical, namely a performic acid. So the vaporized version of formic acid and that performic acid breaks those disulfide bonds. And now these fragments that were initially connected are no longer connected because these two bonds are broken by the vaporized performic acid. Now let's move on to C. So now these two have been broken. And now in step C, we run a second round of gel electrophoresis on that same sheet under the same conditions. But now we run it in a perpendicular direction.