SMAD4 and metastasis: Our results showed that Begg’s funnel plots between SMAD4 and clinicopathological parameters (tumor differentiation, lymph node metastasis, TNM stage, age and sex) were symmetric, and the P values of Egger’s test were 0.600, 0.271, 0.587, 0.700, and 0.482, respectively (Fig. 3).