ARHGEF1 and neoplasm: Although a similar number of CD4+ and CD8+ T cells were found in tumour-bearing lungs of cWT and Arhgef1-cKO mice (Extended Data Fig. 3b), intracellular cytokine staining of T cells from tumour-bearing lungs revealed markedly increased frequencies of polyfunctional cells that co-express two or more cytokines among IFNγ, IL-2 and TNF in Arhgef1-cKO mice compared with cWT mice (Fig. 2a–c).