Lysosomal degradation of extracellular and membrane proteins can be facilitated by lysosome-targeted chimeras (LYTACs). LYTACs are bifunctional compounds composed of a small molecule or antibody that recognizes a protein of interest linked to a peptide that directs the chimera to a lysosome-targeting receptor, such as the cation-independent mannose-6-phosphate receptor. The efficacy with which LYTACs target membrane-associated proteins is hard to predict and often plateaus at 70–80% target degradation. Thus, cell-intrinsic factors may limit LYTAC efficacy. Ahn et al. have now performed an unbiased genome-wide CRISPR screen combined with magnetic bead sorting, to assay cell-surface expression of EGFR, and have identified components of the retromer complex and the neddylation pathway as critical regulators of LYTAC-mediated degradation of EGFR. Inhibition of core components of the retromer complex (such as VPS26A and SNX3), which normally mediates retrograde transport from the endosomes to the plasma membrane, resulted in increased degradation of EGFR of up to 90%. Loss of retromer activity facilitated lysosomal degradation by decreasing recycling of the LYTAC target complex from the endosome to the plasma membrane. Mutations in components of the E3 ubiquitin ligase CUL3-neddylation pathway, which also mediates activation of CUL3, blocked LYTAC-mediated degradation due to the inability of LYTACs to be transported to the lysosomes. CUL3 neddylation was found to regulate the maturation of endosomes to lysosomes, and ubiquitin-based proteomics revealed that CUL3-mediated ubiquitination of SQSTM1, a known ubiquitin-binding protein, is required for late endosomal maturation and LYTAC activity. Loss of SQSTM1 also blocked LYTAC-mediated degradation, with EGFR being trapped in the late endosome compartment. Overall, identification of these cellular effectors of LYTAC activity will inspire design strategies for improving degradation efficacy.