To confirm that protein degradation was dependant on the precise spatial arrangement of the ligands, we designed a series of control DNA constructs. Partial OligoPROTACs were generated by annealing the 3'-(+)-JQ1 OligoPROTAC strand with a non-modified complementary strand (Figure ) and the 5'-VH032 OligoPROTAC strand with a non-modified complementary strand (Figure ). We also constructed an asymmetric OligoPROTAC, where the ligands were on opposite ends of the dsDNA (5'-VH032 and 5'-(+)-JQ1) (Figure , SI Figure ). None of these control constructs were able to elicit BRD4 degradation, thereby, confirming that the activity, i.e. BRD4 degradation, we observed was exclusively due to the OligoPROTAC holding the two PROTAC warheads in the optimal spatial configuration (Figure , SI Figure ). We then benchmarked the best performer, OligoPROTAC [ n =3 ], against the small-molecule PROTAC AT1 to assess its protein degradation efficacy and gain insight into its mechanism of action. To determine the impact of OligoPROTAC concentration on BRD4 degradation, the activity of the two molecules were tested over a 12-hour treatment period. Across all concentrations tested, the OligoPROTAC [n=3] exhibited BRD4 degradation levels comparable to those of AT1 (Figure , SI Figure ). Additionally, a time-course experiment at the highest tested concentration (1 µM) further confirmed that both compounds achieved similar degradation efficiency with time (Figure , SI Figure ). Furthermore, MYC protein and RNA levels were affected, as expected for BRD4-targeting PROTACs (Figure , SI Figure ). We also observed cytotoxicity at similar levels to those induced by the small-molecule PROTAC, assessed by phenotypic changes (Figure ) and CellTiter Glo (Figure , SI Figure ). These results demonstrated that DNA linkers provide comparable efficacy and a similar mechanism of action to small molecule PROTACs, which allowed us to move forward with incorporating DNA nanotechnology to control their activity. To leverage the presence of a DNA linker, we aimed to use toehold-mediated strand displacement, a reaction widely-employed in DNA nanotechnology, to turn "off" the OligoPROTAC (Figure ). For this, we chose to continue with the best performing, mechanistically-validated OligoPROTAC [n = 3]. Initially, we tested 5' toehold sequences of the 3'-(+)-JQ1 OligoPROTAC strand (without the (+)-JQ1) ranging in length from 7 to 10 bases (SI Figure ), based on literature sequences . These were annealed to the previous 5'-VH042 oligoPROTAC strand (without the VH032), which produced a dsDNA construct with 7 -10 base pair-long ssDNA toeholds on one end, and the [n = 3] arms at the other end. As observed by gel electrophoresis, a fully complementary DNA strand to the extended toehold 3'-(+)-JQ1 OligoPROTAC strand (anti-toehold complement), initiated toehold mediated strand displacement and displaced the 5'-VH032 OligoPROTAC strand in all cases. An analogous reaction in cells, should stop the activity of the OligoPROTAC, by separating the (+)-JQ1 and VH032. As all sequences worked, we picked the 8-base toehold for future use, as it had been previously shown to function optimally within cells 28 .