SMAD4 and non-small cell lung carcinoma: NSCLC with clinical stage of IIIA–IV (88.78 ± 13.22 ng/L) showed a lower Smad4 serum concentration than NSCLC with clinical stage IA–IIB (138.43 ± 29.10 ng/L) (P < 0.001) (Table 3; Fig. 2f).