CD274 and cancer: For the tumoral vasculature model in this study, only the A549 cell line was tested, based on prior studies demonstrating that conditioned medium from A549 cells effectively upregulates PD‐L1 expression in ECs.[4, 20] It is worth noting, however, that not all cancer cell types' conditioned media are capable of upregulating PD‐L1 in endothelial cells (Figure S9, Supporting Information).