transgene insertion 1, Constance L Cepko PDGFRalpha-CRE MGI:4837739 transgene Pdgfra-CRE BAC Tg(Pdgfra-cre)1Clc Transgene http://identifiers.org/mgd/MGI:4837739 O Pdgfra-CRE BAC|PDGFRalpha-CRE