Madison, Wis.-based Promega Corp.'s latest offering in this field is the Apo-ONE™ Homogeneous Caspase-3/7 Assay, a kit that, as its name suggests, detects caspase-3 and -7 activity in cell culture. The assay employs a substrate, Z-DEVD-Rhodamine 110, which fluoresces upon cleavage by caspase-3/7; the amount of fluorescence is proportional to the amount of caspase activity present in the sample. The system includes a proprietary lysis/activity buffer that allows one-step, or homogeneous, detection of caspase activity, unlike currently available kits that require multiple steps. "That's one of the key factors that pharmaceutical companies are looking for in their screening applications," explains product manager Pam Guthmiller. "The fewer steps they have in their screening applications, the more cost- effective it is for them to screen multiple compounds," she says. Furthermore, reducing the number of steps produces a faster assay: Apo-ONE can provide results in as little as one hour. Finally, the assay kit offers increased sensitivity; according to company literature, a single assay can detect caspase activity in as few as 400 cells in a 96-well format. Because the assay requires only one step and is easily scalable, it is especially suited for automation and high-throughput screening.