An isolated antibody that has a specific binding affinity to a polypeptide comprising the amino acid sequence HTEGKP (SEQ ID NO: 2) phosphorylated at threonine is provided. The antibody may be used as biomarker for mitotic cells. A method for using the antibody in accordance with the invention comprises contacting a cell with the antibody and detecting antibody bound to the cell as an indicator of the cell being in the mitotic state. A reagent kit comprising the antibody is also provided.
