Evaluation of cellular activity of PROTACs.. HeLa (5 x 10 5 ) and HEK293 (1 x 10 6 ) cells were seeded in standard 6-well plates (2 mL medium) overnight before treatment with compounds at the desired concentration, with a final DMSO concentration of 0.1% v/v. After the appropriate incubation time, cells were washed with DPBS (Gibco) and lysed using 85 µL RIPA buffer (Sigma-Aldrich) supplemented with cOmplete Mini EDTA-free protease inhibitor cocktail (Roche) and benzonase. Lysates were clarified by centrifugation (20000 g, 10 min, 4 °C) and the total protein content of the supernatant was quantified using a Bradford colorimetric assay. Samples were prepared using equal amounts of total protein and LDS sample buffer (Invitrogen).