Evidence suggests that increased activity of the c-abl protein in the brain may contribute to the development and progression of Parkinson’s disease (PD). Nilotinib, a drug that inhibits c-abl, has recently shown promise as a potential therapeutic. In its activated state, c-abl is modified with a phosphate group (protein regulator) and measuring the extent of phosphorylation may be an effective method of determining whether nilotinib is working. Unfortunately, researchers have not yet been able to detect phosphorylation sites due to the low concentration of these proteins in cerebrospinal fluid (baths the brain and spinal cord). To effectively monitor nilotinib in clinical trials, it is necessary to develop a test that can measure these proteins at low concentrations. This project aims to create a test to measure the phosphorylation state of c-abl and its target, CRKL, using the Simoa developed by our lab. We hypothesize that, by using this new technique, we will be able to measure specific phosphorylation states that have not previously been detected. We believe our assays will be instrumental in demonstrating the efficacy of nilotinib in clinical trials, and, in the future, these assays could become a companion diagnostic for the drug. The tests we develop might inform doctors in advance of which people will be most likely to benefit from nilotinib and may even allow them to tailor the dosage of the drug in response to changes in the brain.