SUL enhanced the inhibitory effect of dexamethasone on lung metastasis in a 4T1 xenograft model. 4T1 orthotopic xenograft mice were administered with vehicle, SUL (50 mg·kg−1·d−1), DEX (8 mg·kg−1·d−1) or SUL+DEX (50 and 8 mg·kg−1·d−1) for 2 weeks before being euthanized and undergoing metastasis-related analysis. The harvested lungs were stained with Bouin's Fluid, embedded in paraffin wax, sliced, mounted on slides, and stained with H&E. Images of lungs (A), representative images of H&E staining of the harvested lungs (B), and corresponding quantification of metastatic foci (C). SUL, sulpiride; DEX, dexamethasone. **P<0.01, ***P<0.001.