In previous studies, YM155 was shown to induce apoptosis in leukemia, prostate cancer and breast cancer.36 However, in merkel cell carcinoma, YM155 did not induce apoptosis but inhibited DNA synthesis.37 Survivin is predominantly expressed during G2/M phase of the cell cycle,38 and its inhibition is expected to cause a G2/M arrest. This evidence concerns the gene BIRC5 and breast cancer.