Suspension cells were treated with an apoptosis-inducing agent or DMSO, a negative control, for 4 hours, washed twice, then incubated with ICT’s green caspase 1 inhibitor probe, FAM-YVAD-FMK, for 1 hour and examined under a fluorescence microscope. The top images reveal several experimental cells, all of which fluoresce green, therefore they have active caspase 1. The lower brightfield image at right reveals many control cells in the field of view, however the corresponding fluorescence image is dark (lower left); none of these cells have active caspase 1. Courtesy of Dr. Brian W. Lee, ICT.