Also opposite of observations in primary tumors, TfR1 expression in benign kidney was significantly reduced with RCC tumor progression (Figure 5, Supplementary Figure 3), based on size (p<0.001), grade (p<0.001), stage (p<0.001), sarcomatoid presence (p<0.001) and sarcomatoid percentage (p<0.001). Here, TFRC is linked to renal cell carcinoma.