PDGFRA and renal cell carcinoma: In another work that included tissue samples from 314 RCC patients, the authors found a direct correlation of perivascular PDGFRβ overexpression with the tumor’s advanced stage and grades G3-4.18 In contrast, Tawfik et al19 (2007), who studied surgical specimens from 62 radical surgery patients with RCC, showed that PDGFRα expression did not correlate with the tumor characteristics.