When we performed gene expression correlation analysis for TMPRSS2 and TMPRSS4 genes in GI cancer cell lines, we found a moderate and statistically significant positive correlation for this gene pair in colorectal and stomach cancer cell lines (Fig. 3a, b p-values < 0.05 and R-values 0.613 and 0.559, respectively). The gene discussed is TMPRSS2; the disease is gastric cancer.