CLDN5, CLDN7, and CLDN18 were shown to inhibit the proliferation of human lung squamous cell carcinoma cells by suppressing the phosphorylation of protein kinase B. A study showed that high-dose bevacizumab likely increased tumor invasion and down-regulating CLDN5, which was down regulated by TGFβ1 (25). Here, CLDN5 is linked to squamous cell lung carcinoma.