Several important apoptosis-related proteins, including p53, polo-like kinase 1 (Plk1), caspase-2, Bim (Bcl-2 Interacting Mediator of cell death), and MAPKs ERK and JNK (extracellular signal-regulated kinase and c-Jun amino-terminal kinase) are activated by paclitaxel in breast carcinoma cells; however, Bcl-2 (highly phosphorylated upon taxane treatment) appears to be the most important protein, as its silencing delays mitosis and reduces cell death [160]. This evidence concerns the gene PLK1 and breast carcinoma.