Abstract
Clones of erythroleukemic cells differ in the extent to which they (1) undergo differentiation spontaneously and (2) can be induced to differentiate in the presence of dimethylsulfoxide. Here we demonstrate that relative differences in globin gene expression within and between clones largely reflect differences in the proportion of cells participating in differentiation rather than uniform differences in the extent to which all cells in these clones undergo differentiation. We call this phenotype of a clone its characteristic probability of differentiation, a property that reflects the likelihood that a cell of this clone will undergo erythrodifferentiation under given conditions. We have examined somatic hybrid cells formed between similar erythroleukemic lines, between phenotypically different erythroleukemic lines, between phenotypically different erythroleukemic lines, and between erythroleukemic cells and mouse fibroblasts. Results of these experiments demonstrate that the spontaneous and induced probabilities of differentiation may be altered in an uncoupled fashion, suggesting that each is determined at different steps leading to a common pathway of globin gene expression.