The data indicate that ORM1 expression is increased in both breast cancer tissues and cell lines, and upregulation of ORM1 promotes proliferation, migration, and resistance to epirubicin though increased expression of matrix metalloproteinases 2 (MMP-2) and 9 (MMP-9) and activation of the AKT/ERK signaling pathway. This evidence concerns the gene MMP9 and breast cancer.