The claudin-4 mRNA expression showed no significant change in BC cell lines (5637: 0.88 ± 0.08, UM-UC-3: 0.84 ± 0.46, and T24: 0.98 ± 0.36) over that of noncancer urothelial cell line sv-huc-1 (1.0 ± 0.47, P > 0.05, Figure 2(a)) but was significantly upregulated in BC tissue (15.50 ± 2.76) over that of ANTT (1.0 ± 0.19, P < 0.05, Figure 2(b)). The gene discussed is CLDN4; the disease is breast cancer.