In 2006 first paper describing reprogramming of fibroblast into pluripotent cell, i.e. one that is able to differentiate into all tissues was published. Before that spectacular achievement many projects devoted to study the mechanisms of cell de-differentiation led to the establishment of animal cloning techniques and also derivation of embryonic stem cell lines. Present review summarizes the history of these studies and also describes pioneer works leading to derivation of induced pluripotent stem cells, current methods of reprogramming, and possible applications of these cells.

General characteristics of apoptosis and mechanisms leading to activation of caspases and endonucleases, the main executors of apoptosis is described. The crucial role in these processes of mitochondria and the proteins released from them procaspase 9, cytochrom c and AIF factor is also shown. Information is also presented about membrane receptors, their ligands as well as various regulatory proteins, those from BCL-2/BAX and IAPs families included. It is pointed out that changes in the level of expression and/or properties of regulatory proteins characterize various tumor cells.