SOX3 and gastric cancer: To validate the results of SOX3 in LC‐MS/MS, we assayed the SOX3 levels in the pre‐treatment serums from patients with gastric cancer and healthy controls, respectively, and found that the SOX3 level in patients (693.23 ± 26.21 pg/mL, N = 60) was higher than that in healthy controls (406.45 ± 16.14 pg/mL, N = 60) (Figure 3B; P = .000).