Lung tumors immunolabelled for Cx26 and Cx43 to evaluate if connexin expression changes between primary and metastatic tumors revealed mostly the absent expression of both Cx26 and Cx43 in Cre- (Cx26: 0/2, Cx43: 0/2) and Cre+ (Cx26: 0/5, Cx43: 1/5) mice suggesting that connexins are not upregulated during metastatic progression (Figure 6D, 6E). This evidence concerns the gene GJA1 and metastatic neoplasm.