The transgene is designed with the murine Nanog promoter driving expression of an H2B-EGFP fusion protein (coding sequence for the human HIST1H2BB gene [histone 1 H2bb] with a C-terminal Enhanced Green Fluorescent Protein gene), followed by an internal ribosomal entry site (IRES), a puromycin resistance cassette, and simian virus 40 (SV40) polyadenylation site. (J:220299)