Throughout this work we chose to use literature gold-standard ASO sequences, which have been previous validated using mismatch and scrambled controls. As these sequences had been previously shown to selectively target their corresponding mRNA, the key comparative controls in our experimental validation of (+)-JQ1-ASO conjugates were ASOs without the (+)-JQ1 modification. To test the activity of (+)-JQ1-ASO conjugates, we initially chose a splice-switching ASO (SSO). The 18mer SSO we used contained a fully phosphorothioated (PS) backbone and all sugars with a 2′-OMe modification (Figure ). This gold-standard SSO sequence was developed for the HeLa pLuc/705 cell line , which expresses a luciferaseencoding gene interrupted by a mutated ß-globin intron. The mutation generates a 5′-splice site which activates a cryptic 3′splice site, resulting in incorrect mRNA splicing and non-functional luciferase production (Figure ). The SSO binds to the mutant 5′-splice site and promotes the exclusion of the aberrant intron, restoring the pre-mRNA splicing to produce 10 functional luciferase.