The Rosa-pCAG-LSL-ArchT/EGFP-WPRE-bGHpA-AttB-PGK-frt-Neo-polyA-AttP targeting vector was designed with (from 5' to 3') a CMV-IE enhancer/chicken beta-actin/rabbit beta-globin hybrid promoter (from pCAGGS), an frt site, a loxP-flanked STOP cassette (with stop codons in all 3 reading frames linked to three repeats of an SV40 polyA signal), an ArchT-EGFP fusion gene, a woodchuck hepatitis virus post-transcriptional regulatory element (WPRE; to enhance the mRNA transcript stability), a bovine growth hormone polyA signal, an attB site, a PGK promoter, a second frt site, neomycin resistance gene-SV40polyA signal, and an attP site. The ArchT-EGFP fusion gene is a mammalian codon-optimized cDNA sequence encoding the Archaerhodopsin-3 protein derived from the halophilic bacterium Halorubrum strain TP009 (ArchT or aR-TP009) fused in-frame via a 15 nucleotide linker to the amino terminus of an enhanced green fluorescent protein (EGFP). PhiC31-mediated recombination removed the attB/attP-flanked PGK-frt-Neo-polyA cassette and left a recombined attB/attP site (attL). (J:191265)