The induction of DNA DSBs, as analysed by the expression of phosphorylated histone H2AX (Rogakou et al, 1998), was measured 30 min (Figure 5), and 24 and 48 h (Figure 6) after irradiation of tumour cells, non-treated or pretreated with Hsp90 inhibitors. This evidence concerns the gene H2AX and neoplasm.