passages.id: split_8_test_529_passage
passages.type: progene_text
passages.text: In this study , we demonstrate that uPA stimulates migration of MCF-7 breast cancer cells , HT 1080 fibrosarcoma cells , and uPAR - overexpressing MCF-7 cells by a mechanism that depends on uPA receptor ( uPAR ) - ligation and ERK activation .