Darbufelone is a noncompetitive inhibitor of PGHS-2 (Ki=10±5 μM). Darbufelone quenches the fluorescence of PGHS-2 at 325 nm (lambda(ex)=280 nm) with Kd=0.98±0.03 μM.To test the putative anti-proliferative effect of Darbufelone, A549, H520 and H460 cell lines are used, which are established from three distinct pathological subtypes of NSCLC (adenocarcinoma, squamous and large cell lung cancer respectively). Increasing concentrations of Darbufelone, ranging from 5 to 60 μM, are tested for 72 h. The cell growth inhibition of these three cell lines gradually increases with higher drug concentration. The IC50 of A549 and H520 are 20±3.6 and 21±1.8 μM, respectively, while the H460 has much lower IC50 (15±2.7 μM).