404. That’s an error.
The requested URL /bookmarks/mark?op=add&bkmk=https%3A//stm.sciencemag.org/content/11/488/eaav0936&title=Resistance%20to%20neoadjuvant%20chemotherapy%20in%20triple-negative%20breast%20cancer%20mediated%20by%20a%20reversible%20drug-tolerant%20state
was not found on this server. That’s all we know.