ERBB2 and breast cancer: Du et al. developed PEG-conjugated peptides DH6 (YLFFVFER) and RDH6 (REFVFFLY), demonstrating specific targeting of HER2-positive tumors with good metabolic stability.103 Stefanick et al. also investigated HER2-targeting peptides HERP5, HRAP, KAAYSL, and AHNP for cellular uptake, with KAAYSL exhibiting the highest tumor uptake.104 Hailing et al. developed nanoparticles composed of GE11-modified polylactic-co-glycolic acid (PLGA) and d-α-tocopheryl polyethylene glycol 1000 succinate to deliver salinomycin specifically to breast cancer cells.