STIP1 and renal cell carcinoma: Stress-induced phosphoprotein-1 (STIP1) was further characterised and found to exert two effects: (a) STIP1 promoted the proliferation and migration/invasion abilities of RCC tumour cells and (b) secreted STIP1 promoted the differentiation and activation of osteoclasts and the production of Cathepsin-K—a key enzyme involved in the degradation of the bone matrix [134].