Downregulation of RanBP9 is associated with the development of cancer.42 RanBP9 may function as a tumor suppressor in cervical, colon and lung cancer,43, 44 but may act as an oncogene in breast cancer and renal carcinoma.45, 46 The role of RanBP9 in tumorigenesis remains controversial because of different findings regarding its ability to activate signaling cascades such as ERK1/2 pathway.42, 47 RanBP9 may act as a tissue/cell-specific tumor suppressor depending on its interacting proteins and related regulatory networks. The gene discussed is MAPK3; the disease is breast cancer.