IBSP and prostate cancer: Besides, integrin-binding sialoprotein (IBSP), a phosphorylated and glycosylated matrix protein containing an integrin-binding RGD (Arg-Gly-Asp) sequence, is strongly associated with poor prognosis and bone metastasis in a variety of tumours, including lung, breast and prostate cancers [352–354], and focal adhesion may play an important role in this process [353, 355, 356].