Down‐regulation of phospholipase C‐γ1 during the differentiation of U937 cells

Abstract
Phospholipase C (PLC)‐γ1 and ‐γ2 play a pivotal role in signal transduction for cell proliferation and differentiation. The enzyme activity and protein level of PLC‐γ1 were markedly decreased in the human histiocytic leukemia U937 cell line during the differentiation process which is induced by phorbol 12‐myristate 13‐acetate (PMA) but those of PLC‐γ2 were not altered. Northern blot analysis showed that the levels of PLC‐γ1 and ‐γ2 transcripts were not changed. These results suggest that the expression of PLC‐γ1 during the PMA‐induced differentiation may be down‐regulated by post‐transcriptional processing.