CCI-779 induces apoptosis in a short-term human ALL culture system. A total of 10⁶ lymphoblasts from patients with adult human ALL were aliquoted onto a bone marrow stromal cell layer. All cells were maintained in culture for 24 hours and were either untreated (control) or treated with CCI-779 (100 ng/mL) for 12 or 24 hours. The x-axis depicts patient sample identification, and the y-axis depicts the percentage of apoptotic (annexin V-positive)/CD19-positive cells.