Involvement of tyrosine kinase in growth factor-induced phospholipase C activation in NIH3T3 cells.

Tyrosine kinase inhibitors such as erbstatin and lavendustin derivative inhibited platelet-derived growth factor (PDGF)- and bombesin-induced inositol phosphate formation and phospholipase C (PLC) activation in quiescent NIH3T3 cells. However, bombesin-induced PLC activation was only partially inhibited by tyrosine kinase inhibitors, whereas PDGF-induced activation was completely. Moreover, although bombesin-induced PLC activation was partially inhibited by pertussis toxin alone, this toxin inhibited almost completely in the presence of tyrosine kinase inhibitors. Thus, tyrosine kinase was suggested to be involved in PDGF- and bombesin-induced PLC activation in a different manner.