To assess the impact of protrusion induction on the proteome of mesenchymal-like migratory cells, MDA-MB231 breast cancer cells were seeded on top of collagen-I coated 3 micron transwell filters (corning). No media was added to the bottom chamber and cells were allowed to adhere to filter overnight. The next day, the media on top of cells was refreshed, and the filters were either left with no media in the bottom chamber (closed pores), or with media also added to the bottom chamber (open pores) in order to allow formation of protrusions. Cells were allowed to form protrusions for 2 or 24 hrs, before being lysed and analysed by mass spectrometry, using TMT mediated quantitative proteomics.