Figure 2. Differential expression and interaction of 33 PRGs. (A) Heatmap (blue: low expression level; red: high expression level) of PRGs between the normal and the tumor tissues. (B) The expression of 33 PRG in ESCC and esophageal tissues, tumor, red; normal, blue. The upper and lower ends of the boxes represented the interquartile range of values. The lines in the boxes represented median value. (C) PPI network showing the interactions of PRGs (interaction score = 0.9). (D) The correlation network of PRGs (red line: positive correlation; blue line: negative correlation. The depth of the colours reflects the strength of the relevance). **P < 0.01, ***P < 0.001.