In conclusion, our results demonstrate that the novel anticancer agent GUT-70, a tricyclic coumarin, inhibits cell proliferation by depleting Hsp90 substrates cyclin D1, Akt, and Raf-1, and induces mitochondrial apoptotic cell death with upregulation of Noxa in MCL cells. The gene discussed is HSP90AA1; the disease is mantle cell lymphoma.