Normal Cell Division

There are quite a few variations between normal and tumor cell division. Normal cell division can be broken into four phases: G1, S, G2, and M. During the G1 phase, RNAs are produced, proteins are synthesized and through the P53 gene (also known as the “Guardian of the Genome”), cells are checked for damage and those that are found are forced to go through apoptosis where the cells are forced to “commit suicide” to prevent replication. Through the S phase, the DNA is duplicated and in the G2 phase, proteins are synthesized once more and the P53 gene checks again for mutations in the DNA. Finally during the M phase, the cell splits into two daughter cells through mitosis, matures and the cycle starts once more. Reproduction of cells is caused through cyclins, estrogen, TGF-alpha, and prot-oncogenes. Cylcins are molecules that tell a cell when to enter mitosis. Estrogen allows certain mammary cells to enter the cell cycle and finally the TGF-Alpha, also known as the transforming growth factor alpha, is locally produced in the breast and tells cells when to divide. Proto-oncogenes are normal genes that code for the “go” signal in cell proteins. All four factors affect cell
Because the TGF-Alpha is a protein, when the Proto-oncogenes become damaged, the TGF-alpha will also lead to increased cell division. If the P53 is damaged, the body does not recognize that the cell is damaged, meaning that it can be reproduced. P53 damage is the most common mutation found in breast cancer. Normal cells produce cell adhesion proteins, such as Cadherins and integrins, which bind cells together. As a tumor develops, the production of these proteins decrees. In more advanced tumors, cells break away from their neighboring cells and enter into the blood stream. When a tumorous cell has entered into the blood stream, it becomes