HaCaT reference gene - (Dec/19/2011 )

I would like to know what reference genes you recommand for HaCaT cells. I've read that most of the so-called "housekeeping genes" are not stable in HaCaT and primary keratinocytes ( http://www.jdsjournal.com/article/S0923-1811(07)00344-1/abstract ), while one group, on whose article I've based my experiments, used beta-actin which is described as one of the least appropriate reference genes. In my qRT-PCR i've used beta-actin and B2M as reference genes and none of them seems sufficiently stable.
Which genes do you use? Any ideas about how I can improve my experiments?

You may want to use GeNorm and find the most stable genes yourself...
http://medgen.ugent.be/~jvdesomp/genorm/