Clusterin has been implicated in numerous processes including active cell death, immune regulation, cell adhesion and morphological transformation. Clusterin (previousiy named SP-40) is a glycoprotein, 80 kDa comprising two distinct 40 kDa polypeptide chains. It shows marked similarity, both physicochemically and in immunohistological distribution, to the single chain, 80 kDa, Sprotein, an additional component of the SC5b-9 complex. Clusterin is a secreted glycoprotein of which the exact function remains a matter for speculation.