Cre - Lox

[Mega]

Hi, 

for the cre lox system you usally use two times the same lox sequence (lox - gfp - lox e.g.)

However, there is a small chance of homologous recombination isn't it? 

http://2010.igem.org/Team:Davidson-MissouriW/CreLox

Here are described alternative sites (LoxN) 

And as far as I understand, you could also make "LoxP - GFP - LoxN" whereby the lox'es have slightly different sequences.