Cell proliferation assays and colony formation assay

Cells were seeded in 96-well plates at a density of 5000 cells in quintuplicate. After 24, 48, 72, and 96 h, the number of viable cells was measured with a CellTiter-Glo luminescence cell-viability assay (G3588, Promega). Upon addition of MTS solution, the plate was incubated at 37 °C for 2 h, and we determined absorbance at 490 nm with a plate reader (Tecan, Switzerland).

To assess colony formation, we plated cells at a density of 1000 cells/well in a 6-well plate. After 2 weeks, cells were fixed with 4% paraformaldehyde and stained with 0.1% crystal violet solution for 20 min at room temperature. The plates were photographed after extensive washings and air drying.