Moreover, we used the DRD2 agonists, dopamine and quinpirole, to compete with penfluridol for DRD2 binding and observed that co-treatment with a DRD2 agonist and penfluridol significantly reversed penfluridol-induced upregulation of ER stress and inhibition of cell growth, suggesting that DRD2 is a critical target of penfluridol’s anticancer activities in ccRCC. The gene discussed is DRD2; the disease is nonpapillary renal cell carcinoma.