PA-2 induced a potent cytokinetic effect on ER+ breast cancer cells in vitro and in vivo, mediated via a cascade of events involving a) profound induction of oxidative stress; b) p53 acetylation; and c) translocation of p53 to the mitochondria, culminating in p53-dependent apoptosis and cell cycle arrest, the net result of which is the potent inhibition of tumor growth (Fig. 8). The gene discussed is TP53; the disease is breast cancer.