The increase of the phosphorylation of H2AX at Ser139 (γ-H2AX), a marker of DNA damage repair, was also observed after TAIII treatment, which indicated that TAIII might induce DNA damage in breast cancer cells.These results suggest that TAIII-induced DNA damage activates the DDR pathway, ATM/Chk2 pathway, and causes cell cycle arrest in G2/M phase. This evidence concerns the gene CHEK2 and breast cancer.