inducible mammalian promoter

[NETSCAPE APPLICATION]

Dr. Ryan,
   Thanks very much for your reply.  I was not complete enough in my 
original post.  My problem is that I am working with a liver derived cell 
line; and therefore the mmtv system will cause nonspecific effects.  
Also, I think heavy metal may also cause problems, though I am not as 
sure of this.  For these reasons, I thought that the ecdysone (crustacean 
steroid hormone) system, or something like it might help me.  Any 
suggestions will be greatly appreciated.
Thanks in Advance,
Adam Keeton