Discovery of betulinic acid as a selective inhibitor of human melanoma that functions by induction of apoptosis

Emily Pisha, Heebyung Chai, Ik Soo Lee, Tangai E. Chagwedera, Norman R. Farnsworth, Geoffrey A. Cordell, Christopher W.W. Beecher, Harry H.S. Fong, A. Douglas Kinghorn, Daniel M. Brown, Mansukh C. Wani, Monroe E. Wall, Tina J. Hieken, Tapas K.Das Gupta, John M. Pezzuto