Fig. 4.

PI3-K acts as an intermediary and is required for GRP-induced TACE phosphorylation. (a) PCI-37A cells were serum-starved for 2 days. After pretreatment with the Src family kinase inhibitor PD0180970 (500 nM) for 2 h, cells were treated with GRP or EGF for 10 min. Cell lysates were subject to immunoblotting with phospho-Akt (Ser-473) and total Akt. (b) PCI-37A cells were transfected with p85α siRNA, followed by serum starvation for 2 days and treatment with GRP (400 nM) for 10 min. Cell lysates were subject to Western blotting for p85α expression and TACE immunoprecipitation. IB, immunoblotting; IP, immunoprecipitation. (c) An amphiregulin ELISA was performed on cell culture media according to the manufacturer’s instructions. Cumulative results are shown from four independent experiments (P = 0.014).