The trouble with L cells

[Mr Hassan Abdulrazzak]

Recently I have  transfected L cells with Promega's pCAT-Enhancer vector. 
I used the LipofectAMINE reagent and co-transfected with Pharmacia's pCH110 
(vector containing b-gal reporter gene, expression driven by SV40]. 
I observed a definite signal with this vector on it's own (with out any 
insert !). When I contacted Promega, they answered that this is expected because
( and I quote) " mouse L cells express genes efficiemtly ".
Now what I want to know is has any one had such an experience with 
the CAT-Enhancer vector ? With which cell lines did this problem occur?
Any information about this vector would be appreciated no matter how trivial 
it may seem.
Thank you in advance.

Hassan Abdulrazzak
Molecular Neurobiology Unit
Royal Free Hospital Medical School
Rowland hill Road,
Hampstead NW3 2PF.