SMAD4 and non-small cell lung carcinoma: The concentration of serum Smad4 in patients with NSCLC (109.41 ± 19.51 ng/L) was lower than that in patients with benign lung disease (151.66 ± 34.79 ng/L) and healthy individuals (166.67 ± 36.16 ng/L) (P < 0.001) (Table 2; Fig. 2a).