CDKN1A and renal cell carcinoma: Among these 13 genes, we focused on CDKN1A whose gene product acts as a cell cycle regulator being involved in genomic stability [28] for the following reasons: (i) according to the Human Protein Atlas database for several proteins (PAOX, FBXL15, RAB37, C21orf2) antibodies suitable for immunohistochemical staining are not available or unspecific; (ii) all proteins but CDKN1A are either not or only weakly expressed in renal cell carcinoma, which significantly hampers reliable TMA expression analysis.