After exposure of cancer cells to CPA, 4-OH-CPAUPO, as well as the PPA in concentrations up to 50 μM for HepG2 and 25 μM for MCF-7 for 24 h, the phosphorylation of H2AX (γH2AX), seen as fluorescent foci in cell nuclei, was measured. This evidence concerns the gene H2AX and cancer.