CD9 and breast cancer: Gene set enrichment analysis (GSEA) revealed a signature of gene expression changes related to mesenchymal GBM features (Figure 1A; Table S1, Supporting Information), consistent with a most recent finding that FBXO7 promotes epithelial‐to‐mesenchymal transition (EMT) in breast cancer.[15] We next detected the expression of the most substantially changed genes that are closely associated with the MES‐GBM phenotype (Figure 1B), including CD44, CD9, ID1, and TIMP3, and confirmed that they were all suppressed by FBXO7 depletion (Figure 1C; Figure S1A,B, Supporting Information).