Updated project metadata. Cerebrospinal Fluid (CSF) surrounds the brain and provides it protection inside the skull. It is also used clinically for diagnosis of neurological disorders as well as to monitor disease progression. Neurodegeneration in the brain is known to be associated with altered phosphorylation of proteins expressed in the brain. Most studies have focused on serine/threonine phosphorylation although identification of abnormally tyrosine phosphorylated proteins in CSF can similarly reveal additional biomarkers for neurodegenerative diseases. To achieve this goal, we carried out phosphotyrosine profiling of CSF using phosphotyrosine antibody-based enrichment and high resolution mass spectrometry.