Hi Robert,

Would you provide a reference to what strain, specifically? A link to the Jackson webpage would help. It is unlikely that you are using a Cre knock-in mouse at the endogenous PF4 locus, but are using a transgenic mouse with an engineered PF4 promoter expressing Cre. These tend to be knocked-in randomly, so it is difficult to tell apart mice with one or two copies of the transgene. You may be able to find a reference to the group that made the mouse, in which case you could design your own primers across the region modified on the genome.

Great, thanks for the information! I will check into that, I didn't think of that and you may be correct. In that case I'm out of luck but at least the endogenous PF4 would be untouched. If I don't find my answer I will post back here with a link to the strain. 

Hey Robert! :)

Unfortunately I've tried this already. I've contacted Jackson and tried finding the primer sequences on my own (Jackson said they couldn't give me the sequences). The answer I got was to run qPCR with the primers and hopefully see a 2 fold increase in Cre expression in mice that are homozygous. I haven't tried it yet though. (Mind you this was a couple of years ago when I was trying to breed homozygous lines, so hopefully Jackson might be more helpful now!) 

Leah 

If this strain is from Jackson, it is a hemizygous PF4-Cre transgene. Therefore, you will only see a yes or no expression pattern. Good luck!

Thanks Leah and Rande! Yeah, I was originally thinking of the LysM-Cre mice which have the Cre inserted into the endogenous gene so there can be significant effects of having either a het or homo Cre expressing mouse. But I went back to the original paper and you're correct, and no way to determine other than potentially doing qPCR. Good to know!