Cellular senescence is a physiological state generally defined as a stable arrest of proliferation by preventing the cells from cycling. Unlike terminally differentiated cells, that also do not show proliferative activity, cellular senescence is stress induced and blocks the proliferation of cells with theoretical ability to divide (such as progenitor, stem or cancer cells) due to the activity of specific signaling pathways. The number of senescent cells increases during the ontogenesis of an organism. Senescent cells are not only associated with aging, but also significantly influence this process - a fact that is becoming increasingly well documented.