404. That’s an error.

The requested URL /bookmarks/mark?op=add&bkmk=https%3A//www.pnas.org/content/86/24/9871&title=Expression%20of%20proteinase%20inhibitors%20I%20and%20II%20in%20transgenic%20tobacco%20plants%3A%20effects%20on%20natural%20defense%20against%20Manduca%20sexta%20larvae was not found on this server. That’s all we know.