We have several canine mammary cells with TOP/FOP ratios around 35. To inhibit the active Wnt signalling we use dnTCF in a pcDNA expression vector. The inhibition of the TOP/FOP ratios are however merely the result of increased FOP activity with hardly any effect on TOP activity.
Further experiments showed stimulation of a pGL4.10-TATA[luc2] vector (without TOP or FOP TCF sequences) by empty vectors (pTT3, pcDNA4TO, pcDNAneo and pCS2) in a dose-dependent fashion. We use 1,10 or 100 ng plasmid/vector in a 24 well plate.
Do others recognize this problem or is it species (dog) or tissue (mammary) specific?