The R26 PA-GFP::NLS targeting vector was designed with (from 5' to 3') the CMV-IE enhancer/chicken beta-actin hybrid promoter (CAG; from the pCAGGS vector), a loxP-flanked neomycin-beta-galactosidase fusion protein (betageo) with a STOP codon, a photoactivatable green fluorescent protein (PA-GFP) fused to a nuclear localization signal (NLS), and a woodchuck hepatitis virus post-transcriptional regulatory element (WPRE; to enhance the mRNA transcript stability). (J:202089)