The Ki-67 protein is associated with cellular proliferation, and the protein is present in the nucleus of all cells that are in the active phase of the cell cycle, but absent in resting cells, see [1]. The cell proliferation rate can be assessed by Ki-67-immunohistochemical (IHC) staining, and this can be correlated to the tumor grade and the clinical course. Ki-67 proliferative index is suggested to be an important prognostic variable and is used as a grading parameter for neuroendocrine neoplasms, see [2].
The APP detects Ki-67 negative and positive nuclei, classifies the positive nuclei into 1+, 2+ and 3+ categories, and calculates the proliferation index for neuroendocrine tissue stained for Ki-67.