CTSB and cancer: CtsB can promote tumor development in different ways: first, it is a crucial effector of autophagy supporting cancer cell growth and proliferation; second, increased CtsB activity in the tumor extracellular space (characterized by an acidic pH), results in the cleavage of the basal membrane components, including laminin, collagen V, collagen I, cell adhesion molecules (i.e., E-cadherin) [47,48] and cellular tight junctions.