A 2A-CreERT2-WPRE-pA coexpression cassette is inserted befor the stop codon of mouse Drd1 gene via homologous recombination to establish a tamoxifen inducible Drd1-CreERT2 tool stain. This strain can be used to knockout target gene in Drd1+ cells after tamoxifen treatment when crossed with mice which carry loxp sites flanking target gene.