Immunocytochemistry (Fig. 3B), RT-qPCR (Fig. 3C), and western blotting (Fig. 3D) revealed that the expression of STEAP1 in the three lung cancer cell lines (A549, H460, and H1299) was significantly higher than that in the normal lung epithelial cell line BEAS-2B; the expression of STEAP2 in the three lung cancer cell lines (A549, H460, and H1299) was significantly lower than that in the normal lung epithelial cell line BEAS-2B. The gene discussed is STEAP2; the disease is lung cancer.