H1975 cells were treated with LS1-Biotin-S3B (2 μg/mL) or Biotin for 72 hours. After treatment, the cells were harvested and lysed in a buffer supplemented with a protease inhibitor. The cell lysate (600 μL) was incubated with 25 μL of streptavidin magnetic beads (MCE#HY-K0208) at 4°C for 4-6 hours with rotation. Following incubation, the beads were washed five times with PBST washing buffer, with excess buffer carefully removed after the final wash. The proteins pulled down from the beads were separated by SDS-PAGE and then silver-stained. Differential gel bands were excised, and the proteins on the gel bands were analyzed by mass spectrometry.