Next, we examined the correlation between high COL4A1 expression levels and the infiltration of the two types of stromal cells, CAFs and TECs, in LGG, PAAD, SKCM, and STAD as high expression levels of COL4A1 in these tumor types were correlated with poor patient survival rates in the previously conducted analysis using the TIMER 2.0 tool. The gene discussed is COL4A1; the disease is neoplasm.