RPS6KA1 and cancer: Recently, Yuan et al. designed a combinatorial siRNA-based approach to functionally discern the link between KRAS downstream effectors and phenotypic variation in a large panel of cancer cell lines, and identified two major subtypes within KRAS-mutant cancers based on the dependence on KRAS or RSK (Ribosomal Protein S6 Kinase A1) (25).