The induction of Friend erythroleukaemia differentiation is markedly affected by expression of a transfected c-myb cDNA.

A minigene containing a cDNA encoding the normal mouse p80c-myb protein under strong promoter control was used to transfect Friend erythroleukaemia cells. Expression of the transfected gene was found to result in elevated levels of p80c-myb which were not subject to rapid down-modulation by inducers of Friend cell differentiation as was the product of the endogenous c-myb gene. Continued synthesis of p80c-myb was found to be associated with a marked decrease in differentiation of Friend cells and we concluded that normal down-regulation of c-myb expression may be a necessary event in differentiation of these cells.