To clarify the protumor role of OX40 in pan-cancer ECs, we analyzed open-access data from the Tumor Immune Single-cell Hub single-cell transcriptome database and identified several tumor types with high OX40 expression in the EC subgroup, especially in colon cancer, ovarian cancer, and glioma (Supplemental Figure 4A). Here, TNFRSF4 is linked to ovarian cancer.