BRAF and cancer: The synthetic lethality concept has been used for discovery of anticancer drugs, which may target some genes whose synthetic lethal partners are frequently mutated in cancers but are hardly druggable such as the tumor suppressor genes APC and TP53, or have severe drug resistance such as the oncogene KRAS and BRAF. 11,12 The standard approach to systematical identification of synthetic lethal genes is based on genome-wide or kinome-wide RNAi screening.13 However, large-scale synthetic lethal RNAi screening strategy is laborious and time consuming.