Tyrphostin 8(4-Hydroxybenzylidenemalononitrile) is a potent GTPase inhibitor that inhibits EGFR kinase with an IC50 of 560 μM.Tyrphostin 8 inhibits protein serine/threonine calmodulin phosphatases (IC50=21 μM), enhances transferrin receptor-mediated transcytosis in Caco-2 cells, and increases the hypoglycemic effect of oral insulin-transferrin. hypoglycemic effect.

EGFR:560 μM (IC50), Calcineurin phosphatase:21 μM (IC50)

Pretreated for 20 minutes at concentrations ranging from 10 to 100 μM, Tyrphostin 8 blocks Carbachol-initiated PKCδ tyrosine phosphorylation and ERK1/2 activation in parotid acinar cells[1]. Additionally, at concentrations of 10-100 μM, Tyrphostin 8 induces a rapid and substantial increase in the basal O2 consumption of parotid acinar cells[1]. Furthermore, at a concentration of 100 μM, Tyrphostin 8 reduces parotid ATP content by approximately 90%[1]. In another context, Tyrphostin 8 enhances the apical-to-basolateral transport of insulin-transferrin conjugate by promoting transferrin receptor-mediated transcytosis in filter-grown Caco-2 cell monolayers[2].

In Streptozotocin-induced diabetic rats, Tyrphostin 8 enhances the glucose-lowering effect of insulin-transferrin[2].