Viability assay: Cells were seeded in white 96-well plate (Corning, NY, USA) with increasing concentration (50 nM -25 µM) of inhibitors and respective controls for 48 h. Cell viability was monitored using Celltitre Glo luminescent assay (based on the ATP quantification), following manufacturer's guidelines (Promega). IC 50 for compounds were determined by plotting raw data (normalized to controls) using sigmoid dose curve and nonlinear regression (GraphPad Prism).