Transformation Stability

I was wondering if anyone had any info. on stability of transformed
plants after 3+ generations. By stability I mean no loss in activity
of the integrated transgene.  I have heard that in some cases, after a
few generations, the gene loses activity.  Is it possible that the
genome might slowly reject this foreign DNA, and via gamete formation,
the transgene is slowly (or rapidly) crossed out?  Just a thougt.  

				Jason
				jjgo at gnv.ifas.ufl.edu