COL4A4 and neoplasm: In both the training and test cohort, the gene expression level of COL4A4 was increased in the low clinical stage groups, while the expression levels of COL7A1 and IL6 were increased in the high clinical stage groups (Figure 4A,B), implying that COL4A4 might act as a critical protective factor, while the other two genes are risk factors in tumor development.