Clusterin is an ubiquitously expressed protein of two 40-kD chains, alpha and beta, covalently joined by disulfide bonds. It exists in two forms; a pro-apoptotic form localized to the nucleus and a pro-survival secreted form. Both are thought to be involved in DNA repair and cell cycle regulation. The secreted form is thought to inhibit apoptotic signalling by BAX, Clusterin suppression can sensitise cells to chemotherapy. Clusterin is overexpressed in human prostate cancer, breast cancers and squamous cell carcinomas. Part of the SC5b-9 complex, clusterin prevents the binding of a C5b-C7 complex to the membrane of the target cell inhibiting the complement cascade. Clusterin acts as an extracellular chaperone inhibiting the formation of human lysozyme amyloid associated with Alzheimer