RSU1 and cancer: Given the central role of aberrant ERK signaling in the development and progression of cancer (9, 59, 60), our findings that RSU1, whose expression is frequently lost or reduced in human cancers (37, 38, 39), binds PHB2 and consequently mediates cell–ECM detachment–induced suppression of ERK signaling have important implications for development of therapeutic agents that control cancer progression.