Formation of DNA DSBs in Dox-treated GIST was assessed by a single cell electrophoresis (a Comet assay) and expression of histone H2AX (γ-H2AX) phosphorylated at Ser139 residues, a well-known marker for DSBs, was also used for these experimental settings. The gene discussed is H2AX; the disease is gastrointestinal stromal tumor.