CTLA4 and neoplasm: Alongside TNFRSF4/OX40 and TNFRSF9/4-1BB, we selected a number of markers of tumor-resident Tregs (CTLA4, ICOS, TIGIT, and FOXP3) and performed k-means clustering for all UPS, MFS, and DDLS samples in the TCGA (Figure 4(b)).