Guo et al[10] investigated the correlation between SMAD4 expression in NSCLC tissues and clinicopathological significance and found that SMAD4 levels were lower in NSCLC tissues, and the low expression of SMAD4 was related to tumor differentiation, lymph node metastasis and the TNM stage of NSCLC patients. This evidence concerns the gene SMAD4 and non-small cell lung carcinoma.