Guo et al found that SMAD4 had a strong correlation with the differentiation and lymph node metastasis of NSCLC patients.[10] However, Xie et al[11] found that SMAD4 expression was not related to the differentiation and lymph node metastasis of NSCLC patients. This evidence concerns the gene SMAD4 and metastatic malignant neoplasm in the lymph nodes.