A potential enhancer fragment from upstream of erm (the entire region of overlap between the GMR9D11 and GMR9D10 fragments) followed by the core promoter and 5' UTR of Hsp70 is fused upstream of the z second intron followed by sequences encoding the transmembrane domain of Hsap\CD4 fused to tdTomato. An endoplasmic reticulum export signal from Hsap\KCNJ2 is fused to the C-terminus of the tdTomato sequences. 3'UTR and polyA sequences from His2Av are present downstream of the coding region.