BCL2 and cancer: Furthermore, previous studies indicate that titanocenes have potent, broad spectrum antiproliferative activity against a range of human tumour cells, including multidrug-resistant cells and cells that overexpress the antiapoptotic Bcl-2, therefore suggesting the potential of this novel range of compound for treating drug-refractory cancers (Kelter et al, 2005; O'Connor et al, 2006).