We conducted an oncology protein array to measure 84 major cancer-related proteins in both A549 cells and A549 EVs and found that EpCAM, EGFR, Dkk-1, Galectine-3, Endostatin, E-Cadherin, FGF basic, Vimentin, and progranulin are the top nine hits (Figure 2A). Here, DKK1 is linked to cancer.