Purpose: Human breast milk, a source of biologically active molecules, has long been utilized in the treatment of various diseases. Among its components, whey proteins have attracted attention for their potential influence on cancer-related metabolic pathways, particularly peroxisome proliferator-activated receptor gamma (PPARγ), a key regulator of tumor progression. The present study aimed to investigate the effects of human milk-derived whey proteins on PPARγ gene expression and cell migration in gastric cancer cells. Methods: Whey proteins were isolated from breast milk collected from ten mothers with infants aged 0–6 months and applied to AGS gastric cancer cells under laboratory conditions. After 48 hours of incubation, total RNA was extracted, reverse-transcribed to cDNA, and PPARγ expression levels were quantified using qRT-PCR. In parallel, cell migration was evaluated through wound healing assays. Results: The results indicated differential regulation of PPARγ expression across samples. A significant increase in expression was observed in samples 3, 4, 5, 6, and 7 (p<0.05), whereas sample 8 was the only group showing decreased expression. Migration assays further revealed that whey proteins from samples 2, 3, 5, and 8 suppressed cell migration relative to controls, while samples 6, 7, 9, and 10 did not exhibit such effects. Conclusion: Overall, these findings suggest that whey proteins from different individuals exert variable effects on PPARγ expression and gastric cancer cell migration, potentially reflecting inter-individual differences in protein composition. Future studies should focus on characterizing individual protein components of whey and their specific contributions to PPARγ regulation and metastasis-related pathways.