a ∣ Downregulation of XIST expression levels activates epithelial–mesenchymal transition (EMT) and MET, leading to stemness, invasion, increased production and release of miR-503, which subsequently induces M2 microglia polarization and T cell responses in breast cancer brain metastases. b ∣ lnc-BM interacts with JAK2 to activate STAT1/STAT3 leading to activation of ICAM1, thereby permitting malignant cell co-option of brain endothelial cells. This also activates CCL2 and induces CCL2-dependent macrophage recruitment to brain metastases. c ∣ MAYA promotes bone metastases via activation of YAP1 and methylation of the Hippo pathway gene MST1, leading to increased connective tissue growth factor (CTGF) and osteoblast differentiation.