Compound C108 is an inhibitor of the GTPase-activating protein (SH3 domain)-binding protein 2 (G3BP2), which is involved in breast tumor initiation.{34400} In a mouse xenograft model of breast cancer, compound C108 (1 uM for 24 hours) reduces the proportion of tumor-initiating cells approximately 10-fold compared with untreated cells. In MDA-MB-453 cells, and in the patient-derived xenograft cell line MAXF 401, it diminishes mammosphere formation.