A targeting vector containing an FRT-flanked puromycin resistance gene upstream of exon 3, followed by T2A, a Cre recombinase/ERT2 fusion, a second T2A sequence, and the monomeric far-red fluorescent protein mKate2 was inserted into the 3' UTR (downstream of exon 3) of the Ccr2 gene. (J:233647)