Figure 4. Experimental verification of four genes in the prognostic signature. (A–H) Immunohistochemical images of expression of the four proteins from the prognostic signature in non-tumor tissue samples (A, C, E, G) and tumor samples (B, D, F, H). (I) mRNA expression levels of 4 ferroptosis-related genes were evaluated using qRT–PCR in ccRCC samples and normal samples. *, P < 0.05; **, P < 0.01; ***, P < 0.001.