Two Lrig1T2A-iCreERT2 lines were generated from two ESC clones. Line 1c2 had a postnatal lethality problem (see here). Thus, line 2f1 was generated.The Lrig1T2A-iCreERT2 allele design. The Lrig1T2A-iCreERT2 allele targeting vector map. The vector was recombineered from a C57BL/6J BAC library clone (NGS sequence of the vector here).Characterization of the sfGFP-iCre-ERT2. (1) A test of the mutated P2A between sfGFP and iCre-ERT2 in Lrig1T2A-iCreERT2 allele for ribosome skip activity. See here for the rationale behind using fusions to histone H2B-sfGFP. Basically, without ribosome skip, the tdTomato fluoresces in the nucleus, which is what one sees in these images. (2) Activity and dim fluorescence of the sfGFP-iCre-ERT2 fusion protein. For additional data on the activity of the sfGFP-iCre-ERT2 fusion protein, see here. For additional data on the in vivo fluorescence of the sfGFP-iCre-ERT2 fusion protein, see here and here.To generate the mice, a stem cell line G4 from a C57BL/6Ncr x 129S6/SvEvTac F1 hybrid mouse embryo was targeted with the vector above. Mice were generated from two stem cell clones, 1c2 and 2f1. Germline 1c2 mice were crossed to mixed background Tg(ACTB-FLPe) mice to loop out the Neo then repeatedly backcrossed to C57BL/6J background while breeding out the FLPe transgene and fixing the X and Y chromosomes to the C57BL/6J background. Germline 2f1 mice were crossed to C57BL/6J congenic Tg(Pgk1-FLPo)/+ mice (Simon Titen, Capecchi laboratory) then also repeatedly backcrossed to the C57BL/6J background as for the 1c2 mice (also see here for more information).Notes on PCR genotyping of mouse lines. Works as is (i.e., the total reaction volume is off by a microliter because the amount of the DNA was doubled to prevent pipetting errors).2308 is a routine PCR genotyping gel of Lrig1T2A-iCreERT2 allele and Lrig1T2A-tdTomato allele mice from backcrosses to the C57BL/6J mice. The two alleles are genotyped with the same primers, and show the same size products.A subline of the 2f1 Lrig1T2A-iCreERT2 homozygotes was generated with intercross of het mice from backcross generation N6. 1941 shows in red box genotyping PCR of weanlings from the 2f1 line N6 het intercross. Bottom band is the knock-in band. Top band i...