Abstract
4-1BB (CD137, TNFRSF9) mediates costimulatory signals important for activation and persistence of cytotoxic T lymphocytes. In this issue of JEM, Oda et al. (https://doi.org/10.1084/jem.20191166) report on a chimeric construction encompassing extracellular Fas and intracellular 4-1BB to dramatically improve adoptive T cell therapy.