40xUAS sequences followed by an Hsp70 basal promoter are fused upstream of sequence encoding Mmus\Cd8a - a mutated 'dfr288' fragment - T2A - GFP. 'dfr288' is a fragment that extends from -99 to +189bp relative to the first annotated stop codon of vvl and which promotes stop codon readthrough in cell culture reporter assays. In this construct the 'dfr288' sequence has been mutated to delete the 3' mRNA stem loop, to determine the effect on stop codon readthrough. If there is no stop codon readthrough, only Mmus\Cd8a will be expressed from the construct. If stop codon readthrough occurs, both Mmus\Cd8a and GFP will be expressed (the T2A peptide ensures they are translated as separate proteins).