ERC1 and fibrosarcoma: In this study we have used three types of cells: MDA-MB-231 human breast cancer cells and HT1080 human fibrosarcoma cells were used as examples of migratory cells accumulating ERC1 at the protruding leading edge, where ERC1 and associated proteins are known to play an important role in the regulation of cell edge dynamics5,11; while COS7 cells were used as a simple experimental system to characterize the formation and behavior of ERC1–positive condensates.