Disclosed is in vitro method of identifying a chemical entity that is capable of inducing the death of a cancerous cell, said method comprising the steps of: (i) introducing a test compound into mitochondria of a first cancerous cell and introducing a control compound known not to induce cancer cell death to a second cancerous cell and (ii) assaying for the binding of the compounds to mitochondrial complex II and the generation of reactive oxygen species within the mitochondria of the first and second cancerous cells, and assaying for death of those cancerous cells by the test and control compounds, wherein the complex II binding, the generation of reactive oxygen species and the death of the first cancerous cell by the test compound relative to the control compound indicates that a chemical entity capable of inducing cell death has been identified
