CTSS and neoplasm: By exploiting the lysosomal system, and in particular lysosomal exocytosis, stromal cells can effectively synergize with tumor cells to deposit large quantities of ECM components (e.g., collagen, laminin, fibronectin, and proteoglycans), and release proteases (e.g., MMPs and cathepsins), and oncogenic signaling molecules (e.g., cytokines and growth factors) (Figure 6).