C12_CD4, which mainly comprised CD4+ T cells from tumors (Fig. 1c and Extended Data Fig. 2c), was associated with high gene accessibility for markers of tumor-infiltrating regulatory T cells (Tregs), including TNFRSF18, ICOS and CTLA4 (Fig. 1d and Extended Data Fig. 2e). Here, CTLA4 is linked to neoplasm.