(a) Competition analysis for the Sirt2 inhibition of GW856804X (0, 1, 2, 4 µM final assay concentration) towards NAD+ (125, 250, 500, 1000 µM final assay concentration). GW856804X is an NAD+-competitive Sirt2 inhibitor. v0, velocity; c, concentration. (b) Chemical structure of GW856804X.