For example, a study by Cho and colleagues used a 3D macrofluidic device to demonstrate the communication between lymphatic vessels and tumor cells through the CXCL21/CXCR7 axis, with lymphatic endothelial cells secreting CXCL21, a chemoattract for breast cancer cells expressing CXCR7, causing invasion of MDA-MB-231 towards the lymphatic vessels (17). Here, ACKR3 is linked to breast cancer.