ResumoNeoplastic cells are the cells that growth persistent, disorientated and excessively being benign or malignant, this phenomenon happens due the cell alternation that allows a cell to begin a disorientated multiplication. The emergence of the cancerous cells is associated to the cell cycle dysregulation and the uncontrol of the mitoses. The process of mitoses is the cell division consisting in the distribution of the chromosomes and cytoplasm components from the mother cell to between the two daughter cells. Such a process is responsible for the multiplication of the single-celled individuals and the growth of the multicellular ones, owing to the cell number increase. The mitosis is divided into 5 phases: Prophase the initial phase, on what an alternation of the nucleus and cytoplasm can be noticeable, with a considerable increase of the nuclear volume and condensation of the chromatin forming the chromosomes. Prometaphase where spindle fibers attach to condensed chromosomes and move it to the poles of the nuclear membrane. Metaphase where the chromosomes are aligned to the center of the nucleus. Anaphase where the centromeres divide, and sister chromatids that are components of the chromosomes move to opposite poles. Telophase where nuclear membrane reforms, chromosomes decondense and spindle fiber disappear. But in the neoplastic cells some negative stimulus prevents the triggering of a series of chemical reactions and morphological events, which must occur in a sequential and orderly, so the cell entails decide whether to advance to the next phase or exit the cycle, and mitosis loses control.