RAC1 mutations promote tumorigenesis in melanoma, non-small cell lung cancer, breast cancer, prostate cancer, colorectal cancer, head and neck cancer, testicular germ cell tumours, glioblastoma multiforme, hepatocellular carcinoma and thyroid carcinoma among others [11,78,86,98–104]. The gene discussed is RAC1; the disease is Familial prostate cancer.