gene regulation in knockout mice

[Don Incognito]

yongwee at hotmail.com ("Yong Wee Wong") wrote in message 
> I am working on the gene differential expression screening (by microarray) 
> using a gene deficient mouse model. In the array screening, there is a gene 
> 3 folds down-regulated. This gene is very closed to the knockout gene on the 
> same chromosome(About 1 000 000bp apart). Has anybody come across this case 
> before in the knockout model? Could this downregulation caused by physical 
> location on the chromosome/ or the transgene? thanks

I imagine it would be more parsimonious to think that the gene you
knocked out directly or indirectly influences expression of the
downregulated gene, not so?

Doctor Mirabilis