To recapitulate endothelial-cell-induced tumor cell dormancy in vitro and to identify endothelial proteins, which can induce tumor cell dormancy, we established a 2D co-culture assay wherein primary human umbilical vein endothelial cells (HUVECs) were cultured with human tumor cells expressing a mutant reporter of p27 (mVenus-p27K−) to detect tumor cells that have entered the G0 phase of the cell cycle [17]. Here, CDKN1B is linked to neoplasm.