Key players in exocytic and endocytic vesicle transport include Rab GTPases. The Rab27B GTPase regulates invasive growth and metastasis in breast (Hendrix et al. J. Natl. Cancer Inst. 2010). We are determined to dissect the role of Rab27B-associated vesicles in induction of invasive growth and establishment of the pre-metastatic niche using cell culture and mouse models and multidisciplinary translational approaches.