RT-PCR validation experiments confirmed a substantial upregulation of TIMP1, PECAM1, and CDKN1A mRNA in ccRCC tumor cell lines (HRC-A498, OS-RC-2) relative to a normal renal cell line (HEK 293), as illustrated in Fig. 6J–L. Here, CDKN1A is linked to nonpapillary renal cell carcinoma.