Moreover, cathepsin S expression also contributes to the polarization of macrophages from types M1 to M2 [182], in addition to autophagosome–lysosome fusion [182], as does cathepsin K expression through its activation of TLR-4 [183], thus collectively contributing to the development of a TME that is supportive of tumor growth [184, 185]. The gene discussed is CTSS; the disease is neoplasm.