RAB31 and breast cancer: This is very similar to our observation, indicating a strongly reduced metastatic capacity of rab31 overexpressing cancer cells in a xenograft mouse model despite the fact that overexpression of rab31 leads to increased proliferation of MDA-MB-231 cells in vitro and high rab31 mRNA levels in (highly proliferating) primary tumor tissue are associated with a poor prognosis in breast cancer patients[15].