Cell proliferation was assessed using E-16-well plates and xCELLigence technology (Acea Bioscience, San Diego, CA, USA, distributed by Roche).19 (link) Cell growth was monitored for 72 h. Microelectrodes, placed on the bottom of plates, were used to detect impedance changes proportional to the number of adherent cells and expressed as the cell index. The impedance value of each well was automatically monitored by the xCELLigence system and expressed as a cell index value. The experiments were conducted in triplicate and repeated twice.
For viability assays, melanoma cell lines were plated in 96-well plates at 5000 cells/well in complete medium. 24 hours after plating, varied doses of inhibitors were added in triplicate. 0.1% DMSO was used as negative control. Cell viability was evaluated after 72-hour incubation with drugs using Alamar Blue fluorescent assay (Life Technologies).