THBS1 and neoplasm: Besides tumor-derived factors, other factors also participate in the reprogramming of the lung microenvironment and promote metastatic outgrowth.132 For example, lipopolysaccharide (LPS)-mediated lung inflammation allows the recruitment of bone marrow-derived neutrophils that release the Ser proteases elastase and cathepsin G to proteolytically destroy the antitumorigenic factor thrombospondin-1 (Tsp-1).