EGF-receptor preps:HELP!

[VOSS at AIMP1.UNA.AC.AT]

Hi netters,
we are trying to prepare EGF-stimulatable EGF-R from pH 8 stripped A431 
membranes. We always get presps with contain an activity which stimulates 
phosphorylation of a test peptide. This phosphorylation can be inhibited by 
a EGF-R specific inhibitor. However, we are never able to stimulate thiis 
actiivity with EGF - which should be possible!
So, what is the trick to prepare EGF-stimulateble membrane preps form A431 
cells?
Looking foreward to your suggestions

Tilman
 
*********************************************************
Tilman Voss Ph.D.
Protein Chemistry Group
Bender+Co
Vienna, Austria
Tel: xx43-1-80105 351
Fax: xx43-1-80105 366
Email: VOSS at AIMP.UNA.AC.AT
*********************************************************