We profiled how cancer associated fibroblast exosomes alter T cells in mouse breast tumor setting using mass spectrometry. Briefly, exosomes were isolated from breast cancer associated fibroblasts from the MCa-P1362 cell line and then applied to primary CD8+ T cells from BALB/c mice. After exposure for 24 hours, T cells stimulated with anti-CD3/CD28 antibodies for indicated times and were harvested and subjected to quantitative proteomic and phosphoproteomic analysis by mass spectrometry to capture changes in protein expression and signaling. Unstimulated cells and stimulated cells not exposed to exosomes were used as comparators.