Overexpression of survivin in the nuclei of cancer cells promotes the G1–S cell cycle transition by releasing p21 (known as a cyclin-dependent kinase [Cdk] inhibitor 1) from Cdk4 to activate the cyclin D1/Cdk4 complex, leading to the phosphorylation of the protein retinoblastoma.54,55. This evidence concerns the gene BIRC5 and cancer.