To determine the role of the down-regulation of survivin in the sensitization of cancer cells to ABT-737, we assessed the influences of survivin knockdown on the cell viability and the results are shown in Figure 4C. Knockdown of survivin resulted in a significantly increased cytotoxicity in response to ABT-737, suggesting the inhibition of survivin was sufficient to potentiate the cancer cells to ABT-737. Here, BIRC5 is linked to cancer.