BMP4 and esophageal squamous cell carcinoma: The formula for calculating the risk score is as follows: Risk score of ESCC = 0.006486756 × expression level of HLA-B + 0.003511031 × expression level of S100A12 - 0.134223077 × expression level of SLC40A1 + 0.785407491 × expression level of FABP9 - 0.021149907 × expression level of CD14 + 0.238292334 × expression level of APLN - 0.226841694 × expression level of BMP1 + 0.315827065 × expression level of BMP4 + 0.00809996 × expression level of FGF19 + 0.118629975 × expression level of IGF2 + 1.008924188 × expression level of OSM - 0.01772927 × expression level of EGFR (Table 1A).