Ovarian cancer has been proposed to evolve through two distinct molecular pathways: type I low-grade pathway tumours have a 5-year survival of 55% and have frequently activating mutations of BRAF or KRAS, whereas type II high-grade pathway tumours with a 5-year survival of only 30% are characterised by inactivating mutations of p53. The gene discussed is KRAS; the disease is ovarian cancer.