An official website of the United States government
The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before
sharing sensitive information, make sure you’re on a federal
government site.
The site is secure.
The https:// ensures that you are connecting to the
official website and that any information you provide is encrypted
and transmitted securely.
Castillo L, Sánchez M, Chapman TE, Ajami A, Burke JF, Young VR.Castillo L, et al. Among authors: chapman te.Proc Natl Acad Sci U S A. 1994 Jul 5;91(14):6393-7. doi: 10.1073/pnas.91.14.6393.Proc Natl Acad Sci U S A. 1994.PMID: 8022794Free PMC article.