We found the MM.1S cells in the PD-1 KO co-culture have more cleaved form of caspase-3, caspase-7, caspase-8, caspase-9 and PARP than the control (Figure 3B), showing that PD-1 KO CTLs lead to an elevated caspase activation in tumor cells. The gene discussed is CASP8; the disease is neoplasm.