<p>An evidence describes the source of an annotation, e.g. an experiment that has been published in the scientific literature, an orthologous protein, a record from another database, etc.</p>
The extracellular space is the space outside of the cell membrane but part of a multicellular organism. The term is typically used for a secreted protein that remains associated with the cell, e.g. as part of the extracellular matrix. It is not used for a protein that is secreted into the blood stream (or other body fluids) of eukaryotic, multicellular organisms, such as insulin or fibroblast growth factors.