Multiple myeloma is a progressive and fatal disease characterized by the accumulation of malignant plasma cells in the bone marrow. Normal plasma cells have long been viewed as end-stage cells that have lost the potential for further proliferation. The longevity of these cells has been estimated to range from several days to several weeks.<sup>26Ho F., Lortan J.E., MacLennan I.C., e al. Distinct short-lived and long-lived antibody-producing cell populations Eur J Immunol 1986 ;  16 : 1297

Cliccare qui per andare alla sezione Riferimenti</sup> Recent evidence, however, raises the possibility that, under some circumstances, plasma cells may survive for a much longer period of time.<sup>52Slifka M.K., Antia R., Whitmire J.K., e al. Humoral immunity due to long-lived plasma cells Immunity 1998 ;  8 : 363 [cross-ref]

Cliccare qui per andare alla sezione Riferimenti</sup> Myeloma cells differ considerably from normal plasma cells in that the tumor cells retain the capacity for proliferation and their lifespan may exceed that of normal counterpart cells, perhaps as a result of overexpression of several antiapoptotic cellular proteins.<sup>21Hallek P., Bergsagel P.L., Anderson K.C. Multiple myeloma: Increasing evidence for a multistep transformation process Blood 1998 ;  91 : 3

Cliccare qui per andare alla sezione Riferimenti</sup> Although tumor expansion in vivo is critically dependent upon both growth and death rates, this article focuses on several aspects of myeloma cell growth control.