FOXP3 and neoplasm: In Treg cells, TCF1 deletion has been shown to upregulate Foxp3, IL2Ra (CD25), and TGFβ1, as well as other activation markers, and are superior at suppressing CD8 T cell proliferation and tumor control (Mammadli et al., 2023; Osman et al., 2021; Delacher et al., 2020).