Encouraged by the consistent and promising degradation results with AS2, we prioritized this compound for further detailed activity profiling. We subsequently assessed its concentrationand time-dependent activity in HEK293 cells (Figure and Figure ). Given that AS2 incorporates a VHL ligand methylated at the benzylic position (MeVH032), we included its direct analogue MeCM11 as benchmark in these experiments. However, MeCM11 failed to induce significant degradation after 4 hours at 1 µM, aligning with previous findings from our group and reinforcing that AS2's superior activity is not simply due to incorporation of a more potent VHL binder. AS2 demonstrated robust pVHL19 degradation, with a half-maximal degradation concentration (DC50) of 24.6 nM, achieving a Dmax of 95% after 4 hours at 1 µM. Notably, AS2 also exhibited a significantly rapid degradation onset with half-life (t1/2) of 21.7 minutes at 1 µM, in contrast to CM11's t1/2 of 85.1 minutes (calculated from , Figure , table). To further elucidate the mode of action of FerroTAC AS2, we explored its dependency on ubiquitination and proteasome activity. The degradation induced by AS2 was effectively blocked by pre-treatment with MLN4924, 49 MG132, and a competitive assay using VH032, confirming the anticipated E3-mediated ubiquitination and proteasome dependence (Figure ).