The targeting vector is designed with, from 5' to 3', a CMV-IE enhancer/chicken beta-actin/rabbit beta-globin hybrid promoter (from pCAGGS), a floxed cassette containing a green fluorescent protein (GFP) sequence and a polyadenylation signal, a myc-tagged endoplasmic reticulum-directed promiscuous biotin ligase sequence (BirA*G3-ER), an internal ribosome entry site (IRES), and an mKate2 red fluorescent protein sequence. This targeting vector, which also includes an attB-neoR-attP cassette, was inserted into the Gt(ROSA)26Sor gene. PhiC31o-mediated recombination removed the neo cassette. (J:101977)