MJN228 is a selective ligand for the lipid-binding protein nucleobindin 1 (NUCB1). MJN228 blocks binding of the probe arachidonoyl ethanolamide-diazirine with an IC50 value of 3.3 µM. MJN228 prevents probe binding to NUCB1 in Neuro2a cells at concentrations as low as 10 µM.