ANGPTL4 is a secreted glycoprotein whose effect on tumor progression is tumor-type- and microenvironment-dependent.18–20 It has been shown that transforming growth factor-beta 1 (TGF-β1) induced ANGPTL4 expression in breast cancer cells, which facilitated breast cancer cells to metastasize to the lung.21 Mouse astrocytes secrete TGF-β2,22 a homolog protein of TGF-β1.23,24 On this basis, we investigated how tumor cells and astrocytes interact to contribute to breast cancer BM through the TGF-β2/ANGPTL4 axis. Here, ANGPTL4 is linked to breast cancer.