Effect of rECP-induced apoptosis on MMP. The MMP of BEAS-2B cells, stained with MitoTracker (Red CMXRos), represents the percentage of the damage in mitochondria. BEAS-2B cells were incubated in the absence or presence of 20 μM rECP, 40 μM rECP or 1 μM staurosporine (STS) for 24 h. After treatment, the MMP of cells was determined by FACS. We gated M1 for calculation of intensity shift. All data represent the arithmetic mean ± SEM. **P < 0.01.