Clontech Tet-system conundrum?

[Jim BLonde]

G'day

I've been trying to develop a stable, inducable cell line using Clontech's
Tet-ON system in HeLa cells.  I've encountered problems trying to get
consistent expression in my cells; less than 10% of them seem to express the
transgene (as observed by GFP-fusion fluorescence).  Even after subcloning a
population, I still never see more than 10% expression.

Has anyone else had this problem?  I wonder if it is due to the inducable
system, or if the problem is related to my gene-of-interest.

Thanks,
Jim
blondejd at mcmaster.ca