Detection of apoptosis-related proteins by western blot

To detect cell apoptosis, 4T1 cells were seeded in a 30-mm dish and cultured overnight. The cells were treated with Ce6, MSN-Ce6 and MC (equivalent Ce6 concentration, 2 μM) for 12 h, respectively, then the cells were replaced with fresh culture medium and exposed to 660 nm irradiation (0.2 Wcm^-2, 2 min). Cells were further cultured for 12 h and collected by centrifugation. Cells were lysed on ice for 40 min in 100 μL lysis buffer and the lysates were collected by centrifugation (12000 rpm, 15 min). Protein concentrations were determined by BCA Protein Assay Kit. Total cellular proteins were separated by SDS-PAGE.