2 g/l HEPES buffer, pH 7.4, under a 5% CO2 atmosphere. Cells were passaged by trypsinization when reaching 70-80% of confluence, about twice a week. For each experiment, all cells were seeded at a density of 104 cells/cm2 in 6- and 96-multiwell plates for cell cycle and cell proliferation analyses, respectively. Lycopene (WS) was dissolved in water at 50˚C within a range from 0.5 to 10 μM and beta-carotene was dissolved in a solution with water and ethyl alcohol. Carotenoids were then added to the plates. Cells untreated (controls) were included on each plate. After 24 h, the culture medium was changed. Cells were then incubated for 48 and 96 hours with daily medium replacement