Shinya Yamanaka: ES cells have two important properties.  The first one: we can proliferate — we can culture ES cells as much as we want.  So from a single ES cell we can have a million, billion or more ES cells within a certain period of time.  The other important property of ES cells is something called pluripotency.  So pluripotency means that we can make any types of cells that exist in our body.  We have more than 200 types of cells in our body.  So we can make those 200 types of cells from ES cells.  So that’s the second important property of ES cells.