Immunofluorescence staining demonstrated significant reductions in STAT3 and downstream proteins (VEGF, cyclin D1, c-Myc, BCL-2, and PD-L1) post-treatment, confirming D11-PROTAC’s ability to downregulate these proteins in tumor tissues (Figs. 6E and S23), aligning with its cellular effects. This evidence concerns the gene CD274 and neoplasm.