In the process of exploring Rac1 inhibitors, there are many gratifying discoveries: for example, the inhibitory effect of NSC23766 on Rac1 can antagonize the drug resistance of tumor cells to targeted drugs, such as fludarabine resistance of chronic lymphocytic leukemia (CLL) cells (147), fluorouracil and cisplatin resistance of gastric adenocarcinoma cells (153), and trastuzumab resistance of BC cells (154). This evidence concerns the gene RAC1 and breast cancer.