Patterns of nuclear proto-oncogene expression during induced differentiation and proliferation of human B chronic lymphocytic leukaemia cells.

Phorbol ester-induced differentiation of human B-chronic lymphocytic leukaemic cells was found to be preceded by a rapid transient induction in expression of the c-jun proto-oncogene, which paralleled that of c-fos. Induced expression of c-myc but not of c-fos/c-jun proto-oncogenes was markedly higher in a proliferating variant leukaemic cell population compared with that seen in typical lymphocytic leukaemia cells. These data suggest that the c-fos/c-jun nuclear oncogenes play a role in induced differentiation, whilst c-myc is more important in the proliferative response of B lymphocytes.