Updated publication reference for PubMed record(s): 26555054. In mesenchymal-like cell migration, cells need to polarise into a protrusive front and a retracting cell body. Apart from proteins, several mRNAs are known to be localised to cell protrusions but to what extent RNA localisation and local translation contributes toward front-back assymetry is unknown. We set out to quantify the relative translation rates of cellular proteins between protrusions and cell-body by Pulsed-SILAC proteomics, using MDA-MB-231 cells, a highly invasive breast cancer cell-line. We utilised a transwell filter based fractionation method in conjugation with pulsed-SILAC. In this method, cells are seeded on top of 3μm transwell filters to enable protrusions to form through the pores of the filters but to prevent the cell-bodies passing through due to the small size of the pores, thus resulting in separation of protrusions and cell-bodies on opposite sides of the filter, which can then be lysed and prepared separately. Prepration of protrusion and cell-body fractions from SILAC heavy vs. medium label pulsed cells then allows for reciprocal mixing and quantification of nascent proteins between protrusions and cell-body. We determined the relative local translation rates of 1150 proteins between protrusions and cell-body from two pulsed-SILAC mixes.