RacGAP1 is overexpressed in many very aggressive cancer phenotypes (e.g., meningiomas, hepatocellular carcinomas, epithelial ovarian cancer, invasive cervical cancer, high-grade breast cancer, colorectal cancer, non-small cell lung cancer, and gastric cancer [16, 18–21, 54–59]), which suggests that it is a new marker with great potential. The gene discussed is RACGAP1; the disease is breast cancer.