Excitation at 405 nm, like 561 nm, is optimal for flow cytometric analyses of J-aggregates. L1210 cells were incubated with DMSO (control) or 1 μM valinomycin for 30 min at RT and then stained with 2.5 μM JC-1 for additional 15 min. The control and valinomycin treated cell populations were mixed and analyzed by the LSRII flow cytometer (Becton Dickinson) using 405, 488 and 561 lasers, and 525/50 and 585/42 nm filters. Data were processed using FlowJo v7.6.4. Emission intensities at 585/42 were plotted also as histograms. The 405-nm-excited signal (grey) was normalized by a factor of 1.5-fold for better visualization.