Nature Communications, Published online: 06 September 2026; doi:10.1038/s41467-026-77155-2 Cytotoxic T cells (CTL) are successfully employed in tumour therapy but understanding how their expansion and effector function is regulated might result in further improvements. Here the authors show by a T-cell-specific deletion of Prmt7 and by developing a PRMT7-targeting PROTAC degrader that PRMT7 is a negative regulator of the NF-κB pathway in CTL, removing of which improves anti-tumour function of CTL.