For example, rotenone and metformin (Table 1), widely recognised inhibitors of complex-I of the ETC, inhibit proliferation in several human cancer cell lines,69,70 including prostate cancer.71 PTEN-null cells are highly sensitive to inhibition of complex-I, as their glucose levels are known to be rapidly depleted when ETC is suppressed, which highlights the potential clinical utility of complex-I inhibition of ETC. Here, PTEN is linked to cancer.