The Cell Cycle: Mitogen

The Cell Cycle investigates the mechanisms and substances that regulate cell division and growth. The process of deciding to divide, or not, is a highly regulated interplay of messages and receptors reporting on the state of the environment and the state of the cell. While contemporary conditions have prompted most animal species to initiate an evolutionary process of shrinkage, humans continue to grow taller. Twenty-first century Homo sapiens is the tallest human species of all time. Our contemporary cell climate is one of constant high biological and cultural pressure to proliferate, to expand, divide and grow bigger. It is a situation of biological confusion because of an ill-informed and misdirected cultural environment. The global human body is manipulated into expressing growth as the best strategy for longterm survival while in fact shrinking would be the more rational and sustainable choice.

The divisive processes within the cell cycle that express this confused situation are initiated by mitogens, the signals involved in giving the green light to go ahead at a critical point in the cell cycle. A mitogen is an intermediate agent between the cell and its environment that encourages, if conditions seem favourable, to commence cell division. Mitogens act primarily by influencing a set of proteins which are involved in the restriction of progression through the cell cycle, especially checkpoint G1. Before clearing the checkpoint in G1 the cell can still abort the process of division. After G1 is passed growth abortion becomes much more complicated as the cell is able to continue autonomously without the need for external signals. If mitogens are over-expressed they may cause growth that is unnecessary or even damaging, like in cancer as well as the irrational increase in human height. Both symptoms are defined by a lack of, or failure of, control in the cell cycle. Mitogens can cause the cell cycle to move forward when in fact it shouldn’t. In normal cells this would be corrected by mechanisms designed to prevent the uncontrolled growth of cells, internal or external. Current signalling in and around the cell has allowed the human species to grow to an unprecedented size that poorly reflects global environmental conditions. Pressure on our resources has never been greater. Unless we study mitogen from the position of a desire of non-proliferation we will never understand how global height can be decreased.