Experimental studies of secondary lymphedema in mice demonstrated that collector lymphatics exhibit a gradual decrease of contractility during disease development, and lymphatics positive for the lymphatic marker lymphatic vessel hyaluronan receptor-1 (LYVE-1) (i.e., initial and/or precollector lymphatics9) become profoundly enlarged, involving active proliferation of lymphatic endothelial cells (LECs).5 Here, LYVE1 is linked to lymphedema.