Picture the mechanisms that govern the behavior of a cell as an enormous puzzle. Each piece represents a critical function responsible for some aspect(s) of cellular behavior. In normal cells, all of the pieces fit perfectly. Those that touch one another represent communicating functions that carry vital chemical signals from one point to another in the cell. This function-to-function communication or signaling contributes to the normal control of growth and differentiation and the failure of a cell to develop neoplastic characteristics.
In a cancer cell, some of the pieces do not fit, because of distortions of shape, size, or both. Others are lost altogether. Yet others are abnormally replicated, sometimes many times over. By comparison with that of a normal cell, the picture that emerges from a cancer cell puzzle is disorderly. However, it is still a picture of limited size and shape, and discoveries of the last 20 years
Livingston DM. Genetics Is Coming to Oncology. JAMA. 1997;277(18):1476-1477. doi:10.1001/jama.1997.03540420072033