We found that the mRNA expression of CLDN3, 4, 6, 7, 9, and 14 was higher in BC tissues than in normal tissues (Figure 2A, 2B, 2D, 2E, 2G, 2I), whereas the mRNA expression of CLDN5, 8, 11, 15, 19, and 20 was higher in normal tissues than in BC tissues (Figure 2C, 2F, 2H, 2J–2L). The gene discussed is CLDN3; the disease is breast cancer.