404. That’s an error.

The requested URL /bookmarks/mark?op=add&bkmk=http%3A//www.pnas.org/content/88/7/2898&title=A%20single%20gene%20encodes%20membrane-bound%20and%20free%20forms%20of%20GP-2%2C%20the%20major%20glycoprotein%20in%20pancreatic%20secretory%20%28zymogen%29%20granule%20membranes. was not found on this server. That’s all we know.