Identification of proteins in CRBN protein-protein interaction. Schematic diagrams show the workflow designed for identifying CRBN-binding partners via Co-IP or Ni⁺ beads pull-down and proteomic-based analysis. The first approach includes Co-IP, separation by SDS-PAGE, in-gel digestion and peptide extraction, and HPLC-ESI-MS/MS quantitative analysis. The second approach included using Ni⁺ beads to pull down the proteins from control cells (OCI-MY5 vector) and CRBN-overexpressing cells (OCI-MY5 CRBN-His) untreated or pre-treated with lenalidomide for 48 hours, separation by SDS-PAGE, in-gel digestion and peptide extraction, and HPLC-ESI-MS/MS quantitative analysis.