Nitric oxide (NO), synthesized from L-arginine by NO synthases, is a small, diffusible, highly reactive molecule with dichotomous regulatory roles under physiological and pathological con- ditions. Apoptosis plays an important role in the development of the organism but also under various pathological conditions. NO can exert both pro- and anti-apoptotic effects, depending on the conditions and cell type.

The importance of the effect of infection with human papilloma virus (HPV) , and the processes of carcinogenesis, apoptosis has been the subject of many studies , but is still little understood. The study aims to present the current knowledge of the impact of HPV infection on selected aspects of the processes of life and death of cells. Apoptosis is a complex process which leads to cell death , wherein the protein plays an important role of BCL - 2 family , as well as the cell cycle regulatory proteins include P53 and pRB .

Most of the currently used anticancer drugs and radiotherapy induces apoptosis by DNA damage or inhibition of key enzymes involved in cell survival signaling pathways . This triggers a cascade of reactions leading to the activation of pro-apoptotic proteins Bcl- 2 family , such as Bad , Bid , Bax or Bak , forming a specific channel or coformation of megachannels ( mPTP ) in the outer mitochondrial membrane , allow the release of apoptogenic proteins , such as cytochrome c , Smac / DIABLO , AIF , Omi/HtrA2 , procaspase 9 and 3 and endonuclease G.

The aim of this review is to present a concrete model of apoptosis, namely the physiological death of mammary epithelial cells, and put emphasis on the role of Bcl-2 related proteins in the regulation of this process. The `paper is based on the literature and our own observations related to the regulatory mechanisms of mammary gland remodelling.