Updated FTP location. The CRL4-FH-CRBN complex was purified from 293T cells stably expressing FH-CRBN and stained with CBB following SDS-PAGE. The purified complex was incubated with various cell extracts for 24 h in the presence or absence of pomalidomide. Bound proteins were then affinity-purified using anti-HA beads and subjected to SDS PAGE and CBB staining. Gel slices were prepared and subjected to MS.