MTT assay

Following appropriate treatment, the viability of SW1116 and HCT116 cells cultured in 96-well plates was measured using the MTT assay, as previously described (13). Following 24 h, various concentrations (0, 20, 50, 100 and 200 µM) of Form were added and incubated for 24, 48, or 72 h. After the media and Form were discarded, the cells were incubated with 0.5 mg/ml MTT (Sigma-Aldrich; Merck KGaA, Darmstadt, Germany) at 37°C for 4 h. The medium was then removed and 150 µl DMSO was added to every well. The mixtures were agitated for 15 min in the dark. The optical density of each well was measured using a microculture plate reader (Omega Bio-Tek, Inc., Norcross, GA, USA) at a wavelength of 490 nm.