GAPDH-IN-1 (Compound F8) is a GAPDH inhibitor ( IC 50 of 39.31 μM for GAPDH enzymatic activity). GAPDH-IN-1 forms a covalent adduct with an aspartic acid in the active site to displace NAD + , a cofactor of the enzyme , with concomitant enhancement of the cysteine-reactive probe reaction with the catalytic cysteine.