In this study, GUT-70 demonstrated antiproliferative and proapoptotic activities with more prominent efficacy in mt-p53-bearing MCL cells than in those with wild-type (wt) p53. GUT-70 showed binding affinity to Hsp90, and reduced expression of Hsp90 client proteins such as mt-p53, Raf-1, cyclin D1, and Akt. The gene discussed is TP53; the disease is mantle cell lymphoma.