PLK1 and neoplasm: CRAF directly interacts with key regulators of mitotic progression, polo-like kinase 1 (PLK1) and Aurora kinase A (Aurora-A).233,234 At the G2/M transition during mitosis, CRAF phosphorylation (Ser338) induces protein localization to centrosomes and mitotic spindle poles, where CRAF interacts with and activates Aurora-A and PLK1, leading to mitosis and tumor growth.