HSP90AB1 and neoplasm: Unlike conventional Topo II inhibitors, such as VP16, QA does not produce broken DNA at either the enzymatic or cellular level, and it is a Topo II catalytic inhibitor, unlike traditional Hsp90 inhibitors, such as 17−AAG, which is shown to induce HSR to improve the expression of Hsps and improve the survival rate of tumor cells in incubation for long periods of time and under high concentrations (Figure 5D,E).