FLT1 and nonpapillary renal cell carcinoma: To further explore the identified target genes, we carried out immunohistochemical staining on 170 cases of sunitinib treated ccRCC cases to investigate protein expression of SAV1, VEGFR1 (FLT1 gene) and BLIMP1 (PRDM1 gene), as well as PD-L1, which we had previously identified in our cell model of sunitinib resistance but was not identified in the current analyses [28].