The biological process termed Epithelial-to-Mesenchymal Transition (EMT) plays a central role in cancer cell invasion, metastasis, self-renewal and resistance to therapy(1,2). Here, using western blot technique, we show that H3K9me2 decreases when MDA-MB-468 breast cancer cells undergo EMT upon EGF. We validate this decrease by performing high-resolution MS/MS spectrum. Interestingly, we find that H3K9me2 is associated with mesenchymal genes regulation. 1. Nieto, M. A., Huang, R. Y., Jackson, R. A. & Thiery, J. P. EMT: 2016. Cell 166, 21–45 (2016). 2. Puisieux, A. & Brabletz, T. & Caramel, J. Oncogenic roles of EMT-inducing transcription factors. Nat. Cell Biol. 16, 488–494 (2014).