Because of Hsp90 influencing the cell cycle at multiple levels, either directly or indirectly, Hsp90 function is indispensable not only for organismal development but also for tumor cell progression, which was recognized early on through targeted inhibition of Hsp90 function using ansamycin inhibitors such as geldanamycin and 17-AAG [2,40,41,42]. The gene discussed is HSP90AA1; the disease is neoplasm.