Updated project metadata. To address the challenges associated with the investigation of brain-metastasized cancers and provide insights into the drivers of cancer cell behavior at the brain metastatic site, this study was aimed at exploring the response of SKBR3/HER2+ cells to neural factors secreted by brain cells that come first in contact with the metastasized cancer cells, i.e., human endothelial cells (HBEC5i), astrocytes (NHA), and microglia (HMC3). To this end, serum-starved breast cancer cells were exposed to the combined secretome of brain cells, allowed to grow for 24h, and analyzed by LC-MS/MS using an Orbitrap QE instrument to generate and compare the whole cell proteome profiles of treated vs non-treated cells.