SELL and neoplasm: Consistent with T cell phenotypes in an antigen-free environment, both the bystander memory and tumor-specific cells isolated from the spleens of naïve mice showed a quiescent phenotype as elucidated by low levels of expression of GzmB, the exhaustion markers PD-1 and TIM-3, and high expression levels of the pro-survival marker Bcl-2 and lymph node homing marker L-selectin (CD62L) (Figure 2A).