ETV4 and breast cancer: However, it also has been reported that PEA3 can play a positive role in HER2-mediated breast cancer progression (Myers et al., 2006) and that it can function as an oncogene through up-regulation of MMPs both in breast and ovarian cancer (Barrett et al., 2002; Bieche et al., 2004; Cowden Dahl et al., 2007).