RENBP and neoplasm: Effector-like CD8POS T cells require various signals to become activated and functional, including Ag recognition (signal 1), co-stimulatory signals (signal 2), and cytokine signaling (signal 3).64,65 We have shown that tumor-associated CD8POS T cells were susceptible to DC-provided MHC-I-mediated Ag cross-presentation (signal 1) and rIL-12-based cytokine stimulation (signal 2) (Figure 3A), but we could not verify co-stimulation (signal 3).