dhfr vectors: who has them?

[Edmond]

Hello all,

I was wondering if anyone knows of who may have (commercial or otherwise) a
mammalian expression vector with dhfr in it, as well as a nice multicloning
site.  Hopefully something with a know sequence...the stuff ATCC has contains
little information re sequence.

I plan on using it with CHO/dhfr- cells for some gene amplification studies.

Thank you all in advance,

E