SFRP1 and neoplasm: RAB37 has been identified to be a tumor suppressor and it regulated exocytosis of several proteins including TIMP metallopeptidase inhibitor 1 (TIMP1) 10, 11, secreted frizzled-related protein-1 (SFRP1) 12, thrombospondin-1 (TSP1) 13, and soluble ST2 14.