Similarly, tumor ECs (TEC) identified as CD31‐positive cells in allografted tumors, both from MC38, a highly vascular tumor (colon adenocarcinoma) and the less vascular B16F10 (melanoma), were rendered generally over 90% tdTomato positive (Figs 1B–D and EV1I). This evidence concerns the gene PECAM1 and colon adenocarcinoma.