BCL2 and neoplasm: In a mouse model, tumour-infiltrating T cytotoxic lymphocytes have been divided according to their immunophenotype into 4 groups: (1) T lymphocytes with a functionally depleted cell phenotype (PD-1high, LAG3++, TIM3++), (2) terminally differentiated T lymphocytes with an activated phenotype (PD-1+, LAG3int, TIM3int), (3) T lymphocytes at an early stage of differentiation (Tbetint, CD86+, PD-1+/−, Bcl2+), and (4) apoptosis-resistant migratory T lymphocytes (PD-1−, CD62L+, Bcl2++) [13,38].