Fine-mapping from the cell-division cycle, particularly the identification of mitotic kinase signaling pathways, provides novel possibilities for cancer-drug discovery. Like a key regulator of multiple steps during mitotic progression across eukaryotic species, the serine/threonine-specific Polo-like kinase 1 (Plk1) is extremely expressed in malignant cells and works as a negative prognostic marker in specific human cancer types . Here, we report the invention of the potent small-molecule inhibitor of mammalian Plk1, BI 2536, which inhibits Plk1 enzyme activity at low nanomolar concentrations. The compound potently leads to a mitotic arrest and induces apoptosis in human cancer cell lines of diverse tissue origin and oncogenome signature. BI 2536 inhibits development of human tumor xenografts in nude rodents and induces regression of huge tumors with well-tolerated intravenous dose regimens. In treated tumors, cells arrest in prometaphase, accumulate phosphohistone H3, and contain aberrant mitotic spindles. This mitotic arrest is adopted with a boost in apoptosis, detectable by immunohistochemistry and noninvasive optical and magnetic resonance imaging. For addressing the therapeutic potential of Plk1 inhibition, BI 2536 has resulted in studies in patients with in your area advanced or metastatic cancers.