2.4. MTT Assay

The morphology of treated cells was observed using an Eclipse Ti-U microscope (Nikon; Kanagawa, Tokyo, Japan). Adherent cells were incubated with MTT (0.5 mg/mL) for 2 h, and formazan crystals were dissolved by adding dimethyl sulfoxide. The absorbance at 570 nm was measured using a Synergy HTX microplate reader (BioTek; Winooski, VT, USA), and relative cell viability was calculated as a percentage of the untreated controls.