MCF-7 cells at the density of 1x104 cells/well were seeded on adherent 96-well flat-bottomed plates and cultured as monolayers in complete medium for 48 h 18 (link). Then, PrestoBlue Cell Viability Reagent 10X solution (ThermoFisher Scientific) was added in each well at a 10% final concentration. Fluorescence was measured at 530 nm excitation and 590 nm emission on a Wallac VICTOR2 multiwell plate reader (Perkin Elmer, Milan, Italy) 4 h after dye addition.