Assessment of mitochondrial membrane potential (Δψm)

Measurement of Δψm was performed using the fluorescent probe JC-1, as previously described (17). At low Δψm, JC-1 exists primarily in a monomeric form and produces green fluorescence. At high Δψm, JC-1 aggregates in intact mitochondria and yields red fluorescence. In brief, T24 and 5637 cells were incubated for 30 min at 37°C with 2 µM JC-1 (Molecular Probes, Inc.; Thermo Fisher Scientific, Inc.). Cells were collected and analyzed by the FACSCanto II flow cytometer using FlowJo software version 7.6.1. Results are expressed as the red/green fluorescence intensity ratio; whose reduction indicates loss of Δψm.