Natural History of the Myeloma

The last step iri differentiation is the conversion of a committed ividing stem line cell into a nondividing one making a specialized product. Examples of 'dead-ends ' are red cells, liver paren-chymal cells, neurons, and plasma cells. Clearly, most specialized activities are of no value to the cell carrying them out, e.g., hemoglobin, hormone, antibody synthesis. In order for a slave-cell civilization to be stable, the division of differenti-ated cells must be turned off. Were a dividing cell to make a gratuitous product, selection would be strong for a mutant which had lost this ability, and differentiated organisms would be impossible. The analysis of the differentiated function in nongrowing cells is difficult because homogeneous