The following was inserted at the translation start site: a destabilized enhanced cyan fluorescent protein (d2ECFP), a viral self-cleaning 2A sequence, 4 introns and exons of the Ifng gene, a viral IRES, a mutated non-signaling human CD4 cDNA and an endogenous polyadenylation site. Expression at this locus produces ECFP, the Ifng transcript and a non-signaling human CD4. (J:142395)